If Segwit2x gains 90% support before Aug 1st, will BIP148 still go live?

[TechPriest]

I think BIP148 will still go live but its not necessary in anyway.

The problem is bigger, than you could think. BIP148 it's fake way, 'cause in PoW algo ordinary nodes (core wallets) don't play any role in blockchain network. They cant:
https://github.com/trottier/original-bitcoin/blob/92ee8d9a994391d148733da77e2bbc2f4acc43cd/src/main.h#L795

// Nodes collect new transactions into a block, hash them into a hash tree,
// and scan through nonce values to make the block's hash satisfy proof-of-work
// requirements.  When they solve the proof-of-work, they broadcast the block
// to everyone and the block is added to the block chain.  The first transaction
// in the block is a special one that creates a new coin owned by the creator
// of the block.

These things can be done only by miners. Core clients only broadcast and retranslate transaction to miners. But we can use ordinary servers to do this work. So, here is out conclusion:
We need more miners in bitcoin network. Not users. System with 1 miner and 1 million core clients will be centralized. System with 100000 miners and 1 core client will be decentralized.
And, so what? We in PoW. Core clients mustn't rule anything. Only miners. And they don't affect on decentralization of Bitcoin network.

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[DooMAD]

I think this is the consensus most people are coming too and when the time comes around for the hardfork, there will be much less support for it, and it will be blocked.

"Blocked" might be a little overly simplistic.  While it's certainly true that a hardfork is less likely to occur if there is a lack of either adequate hashrate or adequate economic activity, you can't technically "block" a fork on any scale.  If you really wanted to, you could modify a full node client and fork yourself off the network right now.  No one can stop you.  But at the same time, no one would care if it was just one person.  It's a matter of how many people decide that a fork may be viable and how strongly they believe in what they're doing.

The real questions are:

How many nodes and miners are enough for a fork to survive at all and do you have them in sufficient quantity?  And if so, would survival alone be worth the effort and risk if all you've really achieved is the creation of an altcoin?  Or if you have your goals set a little higher, how many nodes and miners are enough to build the longest chain and do you have them in sufficient quantity to change consensus and form new rules for the network to follow?

If you do have the numbers behind you, no one can stop you.  If you don't have the numbers, still, no one can stop you if you really wanted to, but it probably won't be worth trying.  There is no "blocked", just a "risk vs reward" assessment to consider.  Although it's generally considered that a united chain is more rewarding than two split ones.

[tiger2monkey]

The must-read Segwit Decision Tree
posted: 7/17/2017
https://www.cryptoninjas.net/2017/07/17/must-read-segwit-decision-tree/

Fairly comprehensive summary outlining timelines and scenarios.

Thanks! Pretty detail and good information.

[Rahar02]

Segwit needs to activate first. BIP 148 is a method by which segwit can activate. Segwit2x is another method by which segwit can activate. Neither of those are necessary as segwit has its own method by which it can activate.

Honestly, I didn't get what you mean, it seems surrounding on a circle, never end.
Neither of those are necessary? This words refers to? BIP148 and segwit2x?
Segwit has it own method to be activated, through miners signaling BIP141 or whatever is that?
But, I thought that segwit2x will be lock-in if most miners running the new BTC1 software which signaling BIP91 and could get enough hashrate reach over 80% for 336 block.
Nonetheless, BIP91 is a combination of segwit2x and BIP148, so we can conclude if segwit2x gains hashrate over 80% for 2,5 days, no need for August 1st (BIP148).

[DooMAD]

Segwit needs to activate first. BIP 148 is a method by which segwit can activate. Segwit2x is another method by which segwit can activate. Neither of those are necessary as segwit has its own method by which it can activate.

Honestly, I didn't get what you mean, it seems surrounding on a circle, never end.
Neither of those are necessary? This words refers to? BIP148 and segwit2x?
Segwit has it own method to be activated, through miners signaling BIP141 or whatever is that?

It sounds as though you've answered your own question.  Yes, SegWit could in theory be activated by BIP141, which was the intent of the developers who came up with SegWit.  Although, in practice, that would have proven difficult considering the stance of the miners.  BIP148 (and BIP149, but that just complicates things, so don't worry too much), otherwise known as a User Activated Softfork or UASF was then proposed to force the miner's hands.  But then the miners countered with SegWit2x to combine SegWit with an increase in blocksize.  Because SegWit2x wasn't compatible with either BIP141 or BIP148 due to a different signalling bit, BIP91 was created to "plug the gap", as it were.

so we can conclude if segwit2x gains hashrate over 80% for 2,5 days, no need for August 1st (BIP148).

Correct.

[achow101]

Neither of those are necessary? This words refers to? BIP148 and segwit2x?

BIP 149 and Segwit2x are unnecessary for segwit to activate.

Segwit has it own method to be activated, through miners signaling BIP141 or whatever is that?

BIP 141 specifies the actual signaling that needs to be done for segwit to activate. This method is that 1916 out of a 2016 block window must set bit 1 before segwit can become locked in. BIP 148 and segwit2x are mechanisms to force miners to signal bit 1 so that segwit can activate.

But, I thought that segwit2x will be lock-in if most miners running the new BTC1 software which signaling BIP91 and could get enough hashrate reach over 80% for 336 block.

Yes. Once BIP 91 is activated, all miners must then signal for segwit on bit 1 so that segwit can be locked in and then later activate.

Nonetheless, BIP91 is a combination of segwit2x and BIP148,

No, that is completely wrong. BIP 148 is completely unrelated to BIP 91. BIP 91 is part of segwit2x, not the other way around.

so we can conclude if segwit2x gains hashrate over 80% for 2,5 days, no need for August 1st (BIP148).

If BIP 91 activates, then there is no need for BIP 148. BIP 148 will still activate on August 1st, but if BIP 91 activates and is enforced by that time, both BIP 148 and BIP 91 will be following the same consensus rules (that all blocks must signal for segwit) so there will be no split.

[nizamcc]

I am not a technical geek but want to learn more about this BIP148, BIP91, BIP149, SegWit as well as SegWit2x.
Can anyone do a good detailing for each of the above-mentioned terms as well as make me understand about all this (in a simple language if possible)?
Can they also tell me which one of these will be the best in the interests as well as for the health of bitcoins?

[Darooghe]

How much is the probability of hard forking in BTC's network at 1st august?

[achow101]

I am not a technical geek but want to learn more about this BIP148, BIP91, BIP149, SegWit as well as SegWit2x.
Can anyone do a good detailing for each of the above-mentioned terms as well as make me understand about all this (in a simple language if possible)?
Can they also tell me which one of these will be the best in the interests as well as for the health of bitcoins?

Segwit is a capacity increase proposal which includes various fixes for many things in Bitcoin. It is a soft fork and has its own deployment parameters. Segwit can only be activated if 1915 blocks out of a 2016 difficulty retarget period signal for segwit. Signaling for segwit means that once segwit activates, those miners will enforce segwit's consensus rules. Signaling is done by setting bit 1 of the 32 bit block version number.

BIP 148 is a method to get segwit deployed. When it activates, all blocks must signal for segwit on bit 1 so that segwit will activate by its own deployment procedure. BIP 148 activates when the median time past (the median timestamp of the last 11 blocks) is at or after August 1st, 00:00 UTC. There is no miner signaling and it requires that many users and miners enforce the consensus rule change to force miners to mine the blocks that the users want.

BIP 91 is a another method to get segwit deployed. When it activates, like BIP 148, BIP 91 requires that all blocks must signal for segwit on bit 1 so that segwit will be activated by its own deployment procedure. BIP 91 activates when 269 blocks out of a 336 block non-overlapping window signal for BIP 91. Miners signal for BIP 91 by setting bit 4 of the block version number. Signaling for BIP 91 means that miners will enforce BIP 91's consensus rules.

BIP 149 is a plan to redeploy segwit after it reaches its timeout. Segwit's current deployment will expire on November 15th. BIP 149 is a proposal to redeploy segwit with new deployment parameters after November 15th. It specifies that miners can signal for segwit on bit 1 and activate segwit via miner signaling like they can do now with segwit's current deployment. However once BIP 149's timeout is reached (July 4th 2018), if segwit has not activated yet, segwit will then activate at the given timeout.

Segwit2x is a combination of BIP 91 and a hard fork. Segwit2x currently is implemented as first activating segwit via the BIP 91 method, and then 12960 blocks after segwit activates, hard fork from the 4 MB block weight specified by segwit to an 8 MB block weight.

How much is the probability of hard forking in BTC's network at 1st august?

On August 1st at the time that everyone is so fixated on, probably 0. However the probability of a fork between now and the end of August is almost guaranteed. But you are asking us to predict the future, and that is impossible to do.

[nizamcc]

Thanks for the reply. I have few more questions arise that I want to ask.

Segwit is a capacity increase proposal which includes various fixes for many things in Bitcoin. It is a soft fork and has its own deployment parameters.

What is the difference between a hard fork and a soft fork?
I have heard at some places that when a hard fork happens, (few) miners get their operations blocked by a major number of miners who come to a decision to apply some different rules they agreed upon. Is it true? Don't know much about a soft fork.

BIP 148 is a method to get segwit deployed. When it activates, all blocks must signal for segwit on bit 1 so that segwit will activate by its own deployment procedure. BIP 148 activates when the median time past (the median timestamp of the last 11 blocks) is at or after August 1st, 00:00 UTC. There is no miner signaling and it requires that many users and miners enforce the consensus rule change to force miners to mine the blocks that the users want.

BIP 91 is a another method to get segwit deployed. When it activates, like BIP 148, BIP 91 requires that all blocks must signal for segwit on bit 1 so that segwit will be activated by its own deployment procedure. BIP 91 activates when 269 blocks out of a 336 block non-overlapping window signal for BIP 91. Miners signal for BIP 91 by setting bit 4 of the block version number. Signaling for BIP 91 means that miners will enforce BIP 91's consensus rules.

Are BIP 148 and BIP 91 the same? Or is BIP 148 based on the rules of BIP 91 or may be made based on it? What is that bit 1 and bit 4?

Segwit2x is a combination of BIP 91 and a hard fork. Segwit2x currently is implemented as first activating segwit via the BIP 91 method, and then 12960 blocks after segwit activates, hard fork from the 4 MB block weight specified by segwit to an 8 MB block weight.

Block weights? Are you talking about block sizes here? I mean current ongoing block size is 1 MB (correct me if I am wrong), right?

How much is the probability of hard forking in BTC's network at 1st august?

On August 1st at the time that everyone is so fixated on, probably 0. However the probability of a fork between now and the end of August is almost guaranteed. But you are asking us to predict the future, and that is impossible to do.

I also want to ask a question here that if the fork part gets settled here and we don't see a fork atm, will there still be a possibility of a hardfork in the future if any such scalability issues arise?

[TierNolan]

What is the difference between a hard fork and a soft fork?

A hard fork means that anyone who doesn't upgrade is left behind.

It creates 2 chains (forks).  Your coins are duplicated so you have them on both, the first set of them with the original client and the other set with the new client.

The speed of each chain depends on the number of miners who upgrade.  If all upgrade, then the old chain will basically stop.

If none of the miners upgrade, then the new chain will stop (or basically never get started).

The expectation is that normally one or other fork will get most of the miners and the other will be abandoned due to being so slow.

I have heard at some places that when a hard fork happens, (few) miners get their operations blocked by a major number of miners who come to a decision to apply some different rules they agreed upon. Is it true? Don't know much about a soft fork.

BIP 91 means that miners must ignore blocks that don't vote for segwit.  That means that miners who don't vote for segwit will have their blocks rejected and they won't get paid for mining the block.

Are BIP 148 and BIP 91 the same? Or is BIP 148 based on the rules of BIP 91 or may be made based on it? What is that bit 1 and bit 4?

BIP-148 is that some users have said that if miners don't reject blocks which vote against segwit, then they will follow the ones that do.

BIP-148 was a threat and BIP-91 means that miners do what they asked.

Segwit2X is miners saying that they will comply with BIP-148 in exchange for big blocks in 3 months.

Block weights? Are you talking about block sizes here? I mean current ongoing block size is 1 MB (correct me if I am wrong), right?

The "weight" of a block depends on its size.  Some parts of the block are "heavier".  Weight is the new way to measure the size of a block and is part of segwit.  The witness part of segregated witness is "lighter".

I also want to ask a question here that if the fork part gets settled here and we don't see a fork atm, will there still be a possibility of a hardfork in the future if any such scalability issues arise?

Segwit2X says that there will be a fork in 3 months to make blocks bigger.  The miners have agreed to do this.

It will probably be a drama then too.  Some users will probably threaten not to follow the 2MB chain if miners go through with their big block plan.

If that happens with a lot of users and enough miners, then there will 2 versions of Bitcoin.  They could end up with Big Blocks Bitcoin and Bitcoin Classic or something similar.

It is also possible that everyone will agree to a consensus and almost everyone agrees to upgrade.  

If that happens the legacy chain will likely not have enough miner support to continue.  

If THAT happens, then the users who want the legacy fork to continue might hard fork so that they can change the mining rules so they can get their chain going again.  

That would give three forks Big Blocks Bitcoin, Bitcoin Classic (Stalled) and Bitcoin New Mining Rules.

[nizamcc]

That would give three forks Big Blocks Bitcoin, Bitcoin Classic (Stalled) and Bitcoin New Mining Rules.

Thanks a ton for your reply, that made me understand everything better.
Now one more question about these forks is if this fork (chain) thing gets happened and if we will have our coins duplicated on different chains, then which one of all of them will be usable and real? If we have coins on the wrong chain, is there a potentiality of losing all our coins or their possession? How will we be able to know that our coins are currently sitting on which chain? Is all this going to affect the network a lot?

The drama is getting hotter and catching fire quickly, I hope to see the best solution employed/deployed to get everyone out of this situation.

I also wanna know that is all this going to affect the miners alone or the users of Bitcoins too? I know I have become a pain in the head but this is getting tougher to understand which is why I am try hard to get informed from various sources and taking as much knowledge about it as I can before it happens.

[TierNolan]

Now one more question about these forks is if this fork (chain) thing gets happened and if we will have our coins duplicated on different chains, then which one of all of them will be usable and real?

They are all "real".  If 2 of the forks survive (because both have enough miners supporting them), then you will have 2 sets of coins, one set on each fork.

Coins on a dead fork are worthless and can't be moved around.

There is a possible problem if you spend money on one fork, it might also spend on another fork.  The person who you sent the money to would get it on both forks.

That might not be what you want, especially if both coins are still worth something.

This is called a replay attack, because someone takes your transaction on one chain and sends it (replays it) on the other chain.

Making sure replay attacks aren't possible is important.  I am not sure if segwit2x protects against it actually.

This is why the recommendation is to not spend any money for a few days before and after the fork.  Once things have settled down, people will have the replay attack protections worked out.

If we have coins on the wrong chain, is there a potentiality of losing all our coins or their possession?

When the fork happens, you get an exact copy of the coins on both sides of the fork.

How will we be able to know that our coins are currently sitting on which chain? Is all this going to affect the network a lot?

If you run both clients, each one will show your total for that chain.

I also wanna know that is all this going to affect the miners alone or the users of Bitcoins too? I know I have become a pain in the head but this is getting tougher to understand which is why I am try hard to get informed from various sources and taking as much knowledge about it as I can before it happens.

The miners decide which fork moves the fastest.  If 95% of miners go with one fork, then the other fork will have big problems because it is so slow (one block every 3 hours).  

If one fork is much better than the other, due to the rule change, then the miners will get paid more if they mine on that fork.  That would cause miners who just want as much money as possible to switch to that fork.

[Rahar02]

I am not a technical geek but want to learn more about this BIP148, BIP91, BIP149, SegWit as well as SegWit2x.
Can anyone do a good detailing for each of the above-mentioned terms as well as make me understand about all this (in a simple language if possible)?
Can they also tell me which one of these will be the best in the interests as well as for the health of bitcoins?

Segwit is a capacity increase proposal which includes various fixes for many things in Bitcoin. It is a soft fork and has its own deployment parameters. Segwit can only be activated if 1915 blocks out of a 2016 difficulty retarget period signal for segwit. Signaling for segwit means that once segwit activates, those miners will enforce segwit's consensus rules. Signaling is done by setting bit 1 of the 32 bit block version number.

BIP 148 is a method to get segwit deployed. When it activates, all blocks must signal for segwit on bit 1 so that segwit will activate by its own deployment procedure. BIP 148 activates when the median time past (the median timestamp of the last 11 blocks) is at or after August 1st, 00:00 UTC. There is no miner signaling and it requires that many users and miners enforce the consensus rule change to force miners to mine the blocks that the users want.

BIP 91 is a another method to get segwit deployed. When it activates, like BIP 148, BIP 91 requires that all blocks must signal for segwit on bit 1 so that segwit will be activated by its own deployment procedure. BIP 91 activates when 269 blocks out of a 336 block non-overlapping window signal for BIP 91. Miners signal for BIP 91 by setting bit 4 of the block version number. Signaling for BIP 91 means that miners will enforce BIP 91's consensus rules.

BIP 149 is a plan to redeploy segwit after it reaches its timeout. Segwit's current deployment will expire on November 15th. BIP 149 is a proposal to redeploy segwit with new deployment parameters after November 15th. It specifies that miners can signal for segwit on bit 1 and activate segwit via miner signaling like they can do now with segwit's current deployment. However once BIP 149's timeout is reached (July 4th 2018), if segwit has not activated yet, segwit will then activate at the given timeout.

Segwit2x is a combination of BIP 91 and a hard fork. Segwit2x currently is implemented as first activating segwit via the BIP 91 method, and then 12960 blocks after segwit activates, hard fork from the 4 MB block weight specified by segwit to an 8 MB block weight.

How much is the probability of hard forking in BTC's network at 1st august?

On August 1st at the time that everyone is so fixated on, probably 0. However the probability of a fork between now and the end of August is almost guaranteed. But you are asking us to predict the future, and that is impossible to do.

Quote for reference,

Honestly, we expect for segwit could resolve major problems of bitcoin such as high fees and unconfirmed transactions, right?
Most people don't know exactly what the benefits of segwit such as malleability fixes, what else?

According to your explanation,  BIP148 means miners should signaling on bit 1, and BIP91 is miners signaling on bit 4.
I thought When segwit2x has been locked-in, segwit has slightly chance to be activated, or am I wrong?
And to activate segwit, users and miners should enforce the consensus rule change to force miners to signaling on bit 1?  But, if users don't want to, then segwit will be expire on November 15th. My questions are, why user should choose segwit over segwit2x? Or segwit2x is a secret way to activate segwit?  

[achow101]

Honestly, we expect for segwit could resolve major problems of bitcoin such as high fees and unconfirmed transactions, right?

Once people start using segwit transactions, then yes, we should see lower fees and faster confirmations as segwit increases Bitcoin's capacity.

Most people don't know exactly what the benefits of segwit such as malleability fixes, what else?

Segwit fixes a problem known as quadratic sighashing. Quadratic sighashing is an issue where large transactions can take seconds to validate (seconds are a very long time in computer time) because they end up hashing potentially gigabytes of data to verify all of the signatures in a transaction. The problem is quadratic in complexity; i.e. double the size of the transaction and the time to validate it quadruples.

There are a number of other benefits too, many are detailed here: https://bitcoincore.org/en/2016/01/26/segwit-benefits/

According to your explanation,  BIP148 means miners should signaling on bit 1, and BIP91 is miners signaling on bit 4.
I thought When segwit2x has been locked-in, segwit has slightly chance to be activated, or am I wrong?

When BIP 91 activates, it will require that all blocks signal on bit 1 so that segwit can activate via its normal activation. BIP 148 does the same thing too, but BIP 148 activates by date instead of by miner signaling. Since BIP 91 has locked in already, it will activate. And because we are before BIP 148's activation of August 1st, BIP 148 is moot now.

And to activate segwit, users and miners should enforce the consensus rule change to force miners to signaling on bit 1?  But, if users don't want to, then segwit will be expire on November 15th.

Yes.

My questions are, why user should choose segwit over segwit2x? Or segwit2x is a secret way to activate segwit?  

Segwit itself is encapsulated by the segwit2x proposal. Segwit2x includes BIP 91 to activate segwit. But it also includes a hard forking thing that will happen 12960 blocks after segwit activates.

[Rahar02]

According to your explanation,  BIP148 means miners should signaling on bit 1, and BIP91 is miners signaling on bit 4.
I thought When segwit2x has been locked-in, segwit has slightly chance to be activated, or am I wrong?

When BIP 91 activates, it will require that all blocks signal on bit 1 so that segwit can activate via its normal activation. BIP 148 does the same thing too, but BIP 148 activates by date instead of by miner signaling. Since BIP 91 has locked in already, it will activate. And because we are before BIP 148's activation of August 1st, BIP 148 is moot now.

Thank you for your answers.
But I've read about miners which signaling on bit 1 has been declined after BIP91 locked-in, maybe you can see it on bitcoin core wallet or it just fud news? I'm wondering too, what's going on. If they don't use bit 1 or BTC1 (v1.14.4) software, is it matter? As segwit2x should be activated in 2 weeks, right?

I'm waiting for BIP148 which is on mooting right now, whether it still necessary or whatever it could be. My apologies, I'm not an expert on this field.

My questions are, why user should choose segwit over segwit2x? Or segwit2x is a secret way to activate segwit?  

Segwit itself is encapsulated by the segwit2x proposal. Segwit2x includes BIP 91 to activate segwit. But it also includes a hard forking thing that will happen 12960 blocks after segwit activates.

Encapsulated means another way, a secret path to activate segwit
BIP91 includes a hard forking, about 2Mb hard fork, right?
Does hard fork even really necessary? Does bitcoin need 2Mb blocksize?
Thanks.

[achow101]

But I've read about miners which signaling on bit 1 has been declined after BIP91 locked-in, maybe you can see it on bitcoin core wallet or it just fud news?

That is completely incorrect. Signaling on bit 1 has significantly increased after BIP 91 locked in. You can clearly see the increase in signaling of bit 1 over the past day in this graph:

The yellow line is segwit signaling over the last 144 blocks. As you can see, it has sharply increased today as BIP 91 locked in.

I'm wondering too, what's going on. If they don't use bit 1 or BTC1 (v1.14.4) software, is it matter? As segwit2x should be activated in 2 weeks, right?

No. BIP 91 (aka the first half of segwit2x) requires that all blocks after activation must signal for segwit on bit 1. Segwit2x is not a different implementation of segwit. Rather it is a plan to activate segwit via BIP 91 (and BIP 91 activates segwit by requiring all blocks signal for segwit) and then to hard fork later.

I'm waiting for BIP148 which is on mooting right now, whether it still necessary or whatever it could be.

Right now, BIP 148 is theoretically pointless as miners should be enforcing BIP 91. If they do not, then BIP 148 will have an effect as then BIP 148's rules activate on August 1st. However I am told that most miners are running either btc1 (aka the segwit2x client) or segsignal (aka a BIP 91 patch on top of Core) so they will be enforcing BIP 91.

Encapsulated means another way, a secret path to activate segwit
BIP91 includes a hard forking, about 2Mb hard fork, right?

No, BIP 91 does not include a hard fork. That is segwit2x. Segwit2x contains BIP 91, but BIP 91 is not segwit2x.

Does hard fork even really necessary? Does bitcoin need 2Mb blocksize?

Calling it a 2 MB block size is actually completely wrong. The maximum block size would be 8 MB. It does represent a capacity increase, but it may be one that is unnecessary with all of the things that segwit brings us. In fact, such a hard fork could be harmful.

[metalbean]

BIP148 is the forceful way to start Segwit by allowing BIP148 voters to reject non Segwit-supporting blocks.

It's like a pre announced coup in favor of Team-A in the middle of an election.

Segwit2X is Team-A and Segwit is the presidential candidate and 2X his running mate.

[metalbean]

But I've read about miners which signaling on bit 1 has been declined after BIP91 locked-in, maybe you can see it on bitcoin core wallet or it just fud news?

That is completely incorrect. Signaling on bit 1 has significantly increased after BIP 91 locked in. You can clearly see the increase in signaling of bit 1 over the past day in this graph:

The yellow line is segwit signaling over the last 144 blocks. As you can see, it has sharply increased today as BIP 91 locked in.

I'm wondering too, what's going on. If they don't use bit 1 or BTC1 (v1.14.4) software, is it matter? As segwit2x should be activated in 2 weeks, right?

No. BIP 91 (aka the first half of segwit2x) requires that all blocks after activation must signal for segwit on bit 1. Segwit2x is not a different implementation of segwit. Rather it is a plan to activate segwit via BIP 91 (and BIP 91 activates segwit by requiring all blocks signal for segwit) and then to hard fork later.

I'm waiting for BIP148 which is on mooting right now, whether it still necessary or whatever it could be.

Right now, BIP 148 is theoretically pointless as miners should be enforcing BIP 91. If they do not, then BIP 148 will have an effect as then BIP 148's rules activate on August 1st. However I am told that most miners are running either btc1 (aka the segwit2x client) or segsignal (aka a BIP 91 patch on top of Core) so they will be enforcing BIP 91.

Encapsulated means another way, a secret path to activate segwit
BIP91 includes a hard forking, about 2Mb hard fork, right?

No, BIP 91 does not include a hard fork. That is segwit2x. Segwit2x contains BIP 91, but BIP 91 is not segwit2x.

Does hard fork even really necessary? Does bitcoin need 2Mb blocksize?

Calling it a 2 MB block size is actually completely wrong. The maximum block size would be 8 MB. It does represent a capacity increase, but it may be one that is unnecessary with all of the things that segwit brings us. In fact, such a hard fork could be harmful.

I heard somewhere else it's 10mb, can you show me the code?

[Darooghe]

How much is the probability of hard forking in BTC's network at 1st august?

On August 1st at the time that everyone is so fixated on, probably 0. However the probability of a fork between now and the end of August is almost guaranteed. But you are asking us to predict the future, and that is impossible to do.

Isn't Bitcoin science? If it is science you should do prediction the future So could you explain at what conditions the hard fork is inevitable? and how much is the probable of getting those conditions at future?