nothing to see

Pruning is good but not enough. Syncing transactions is a nightmare and what makes pruning almost useless.

And when you receive such a block, how can you tell if the transactions in the block are valid?  What do you compare them to? If you receive multiple different new genesis blocks, how do you know which one is the right one?


Clearly.  If you were, you'd have put a bit more thought into what the current blockchain concept actually accomplishes and how it accomplishes it before trying to replace it without knowing what you need to protect against.

Not about that, it's about the data inside the "new genesis block(s)" which enables some users to delete the older blocks.
How can a node verify the previous unspent transactions that were deleted with the previous deleted blocks?

The usual rules require you to follow the VALID chain with the largest difficulty sum.

By creating a new genesis block, you completely destroy the ability for any node to determine the validity of the UTXO set.  You FORCE the users to accept the chain with the largest difficulty sum instead of the VALID chain with the largest difficulty sum.  This creates a disaster every time there is a new Genesis block.  Any transaction that had MANY confirmations, suddenly has only 1 confirmation.  There is no way to know if that genesis block you just received is the ONLY genesis block out there, or if there are dozens of competing genesis blocks all being worked on by different miners.  You have to wait for multiple blocks all over again to be confident of which funds are actually in the blockchain.  Furthermore, this gives an attacker an opportunity every week to solve just one block and completely re-write whatever funds they want to.  They can create a completely fraudulent block that gives themselves control over most of the funds, and get it broadcast quickly so that it gets built upon.  Once it has a few blocks on top of it, it becomes truth, regardless of what happened before the Genesis block.

Like I already pointed out...

You need to "put a bit more thought into what the current blockchain concept actually accomplishes and how it accomplishes it before trying to replace it without knowing what you need to protect against."


No thanks.  If I plan on trusting, I'll just use the efficient and existing banking infrastructure as provided by governments and private institutions.

If I'm using a blockchain solution, it's specifically so that trusting isn't necessary.

Obstacles that are very easy to overcome but let's make it crystal clear before proceeding any more: There is a decent version of op's proposal called UTXO commitment (as @ETFbitcoin reminded it above) with a very old history in bitcoin discussions and IMO, a delayed_for_no_reason one as well.
Now back to your arguments:
Suppose we ask nodes to commit to the hash of the UTXO they have been using before the fresh block they are working on. This hash is practically representing the state of the blockchain as of the latest confirmed block. Such a commitment could be easily done in the coinbase transaction like what op suggests or segwit is using now.
In such a situation:
1- Upgraded full nodes can trivially verify this state to be the same as theirs, rejecting false claims while legacy nodes remain indifferent regarding this item, hence, it would be a soft-fork.

2- Pruning works better as nodes can confidentially remove larger parts of the blockchain history.

3- Bootstrapping is done in a more sophisticated but efficient way:

• a) A Fresh uninitialized node asks peers to announce their latest block headers, thereafter it continues starting from the heaviest chain claimed:
• b)It calculates the height of the chain by which it can be convinced about its security.
  Suppose the user has chosen 100,000 Zetta hash as its security assurance threshold (an attacker with total hash power of the current bitcoin network being busy for like a week to defraud the user), each block with current bitcoin difficulty represents 60 Zetta hash and if difficulty was fixed this user would need 1,667 blocks long blockchain to be convinced about its security, with a heuristic assumption about possible difficulty change the node chooses 2,000 blocks as being safe.
• c)The fresh node downloads headers from the pear in reverse order from the latest block #N down to earliest, block #(N-2000)
• d) it verifies the integrity of headers just like an SPV wallet.
• e) After downloading block #(N-2000), the node queries the peer for the coinbase it commits to,  extracting the UTXO hash it has committed to afterward.
• f) It downloads the UTXO as it was committed to at block #(N-2000) from the peer. This reflects the state of the blockchain as of block #(N-2001) as long as it is consistent with its committed hash.
• g) Being convinced about the state of the database at block (#N-2000), our bootstrapping node now starts full validation of all 2000 blocks one by one up to block#N.
  

As of efficiency considerations, there are good algorithms and techniques proposed. Check this one for instance:
https://github.com/tomasvdw/bitcoin-abc/blob/utxoflat/src/secp256k1/src/modules/multiset/README.md

What's the difference between the two? Nothing! Absolutely nothing as far as we are talking about less than 250 Million dollars of assets. Do you need more security? Set the threshold to be higher, go for 10,000 blocks it gives you 1+ billion dollars security.

As of "sabotage" attacks: Bitcoin is not about sabotage, it is absolutely out of context. Bitcoin is about the rational behavior of players, not a crazy person/organization who is willing/allowed to waste one billion dollars to create panic and stress in bitcoin (it recovers eventually). Such an attack is never going to happen. Full nodes are not installed and run by people to resist against "sabotage" attacks. You need to review the game theory behind the bitcoin original design, we don't think or talk about irrational behaviors too much, it would be just a distraction.

An attacker with such a huge hash power could easily commit sophisticated double-spend attacks by short-range rewrites against exchanges and individuals instead of wasting his resources to fool some noebs who are setting up new full nodes to keep track of their few thousand dollars worth of bitcoins instead of going SPV! What I'm proposing eliminates SPVs from the ecosystem and allows mobile wallets to be a true full node taking a real part in the consensus and you are worried about "sabotage"? Kidding?

It is pure trolling. I'm absolutely not surprised, you are a known shill  
Otherwise, I'm bad    you need to be good, don't you?
Be a good person and commit to a good idea, instead of bragging with few lines of code other people write. Behind any good code is mathematics and algorithms discussed to death, don't be naive.

You have no clue about what is called "rational" ... I get it now.
An attacker is not a mindless, irrational body. Costs should be justified and there should be incentives ways higher than costs. Is it that hard to understand?
Your "sabotage" argument is void and useless in the context of any discussion about bitcoin. People attack bitcoin to steal funds, not for fun!

This seems to be naive, I'm done reading such "paper"s. Bitcoin core is already immune to such an attack with its checkpoints and the limitation put on the fork length and prevention of forks beyond the checkpoint.

Recently I've provided a strong mathematical base for mitigating this class of attacks:
How far can possibly bitcoin blockchain height diverge from the ideal one- block-per-10-minutes measure?

I did it because of a similar DoS vulnerability proposed by somebody (and fixed later) regarding the bitcoin core getHeaders message. I've mathematically proven that the length of the blockchain regardless of what happens to the network hash rate and difficulty has upper bound and nodes can easily calculate it by looking at their local time and being aware of Jan-3-2009, the Genesis.

It is also possible to establish more sophisticated mathematical measures that compare the claimed chain height with the target difficulty because for a longer chain you need a higher difficulty, as a general trend.

Are you sure? but it is what shills do, they are guardians who try to save bitcoin from aliens  

Report me as a bad employee to the boss, they'll fire me