Mining activities paused & all bitcoins mined, is it same result?

[Queentoshi]

I did a quick search to know what the possible outcome will be if all bitcoin mining activities are somehow paused, this is the response quoted from quora:

That's as if you would have asked what happens if internet gets cut off or light turned off. That's likely not gonna happen but theoretically let's presume it does, all miners stop mining having turned off their nodes. The network will just stop functioning, the mathematical complexity will start dropping to the less complex one “hoping” someone will solve it.

So, the blocks are not mined, transactions don't go through - the whole ecosystem collapses until someone starts mining again.
 

https://www.quora.com/What-would-happen-if-all-blockchain-miners-stopped-mining

Now I am a bit confused since all the bitcoins available for mining is 21 million, if mining activities increase, and all the bitcoins are somehow mined, will the effect be the same as described if all mining activities are paused for the now?

[mocacinno]

Well... I spot an error in the quora answer straight away...
If all miners would turn off their mining equipment, difficulty wouldn't just magically drop. There's a diff retarget every 2016 blocks, and even then the amount the difficulty can increase/decrease is limited (my memory is fuzzy on how much it can rise/drop... You can look it up on github, on the repo of the reference client it's hardcoded... I even posted the exact line in the code somewhere in the past, but i'm to lazy to look it up).

So, if everybody would turn off their mining equipent and there wasn't a hard fork to solve the issue, difficulty would stay exactly as high as it currently is forever. People could still broadcast transactions that would reside in the mempools of the nodes for some time, but no transaction would ever be included in a block (so no confirmations, and as soon as an unconfirmed tx is purged from most mempools, it's like it never existed in the first place).

As for the rest of your question: this has been discussed at lenght so many times before... Just search the forum for questions like "what happens if 21 bitcoins are mined".
TL;DR; the most common answer is that miners should have enough incentive to continue mining because of the mining fees... I'm not sure if that will happen, but i probably won't be around anymore by that time either, so i'll never know if this is/was a correct statement anyways . Maybe we'll have switched to a different algo by then, maybe miners will have enough incentive from the fees alone, maybe people will mine altruisticly, maybe companies using bitcoin will continue mining so their business model is sustainable, maybe bitcoin died long before this point was reached,....

[mikeywith]

Well... I spot an error in the quora answer straight away...
If all miners would turn off their mining equipment, difficulty wouldn't just magically drop.

Also this

internet gets cut off or light turned off

If the internet gets cut off, miners can use other means of communication, like airwaves, for instance, light turn-off is also somewhat solvable, so none of that would totally cause the ecosystem to collapse, the only thing that could destroy it is "absolute lack of incentives", one can interpret that statement in different ways but I think we can all get to the same conclusion.
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