I don't think there is any consensus that we actually want to increase the block size any further for now - that is the main reason why extension blocks have not been deployed. The hard problem is not how to do it technically, but whether we need to do it or whether we should stick to what we have now with Segwit and scale on layer 2 instead.
While the block-size increase was one of the effects of Segwit, it was not the only and perhaps not the most important one. Segwit also solves transaction malleability in an elegant way, which makes the implementation of layer-2 techniques (including Lightning) easier.
Ethereum idol, Vitalik Buterin says it is impossible and there is a law like in thermodynamics that forbids onchain scaling. It is a ridiculous claim and I've refuted it in many occasions.
2nd layer scaling solutions are inherently vulnerable to centralization and no matter how many bitcoin devs are working on it because once you are working on such a protocol you are an outlander for bitcoin community.
The basic axiom of bitcoin and cryptocurrency (unlike what Buterin is trying to sell us) is the possibility of achieving to all of the three characteristics (that he claims to be in a trilemma): security, decentralization and performance in a blockchain.
Axioms are not subject to debate, anybody who thinks we can't have a better performance without jeopardizing security or decentralization is not bitcoiner or a member of cryptocurrency movement. Such a person is just a revisionist probably hired by feds or corps or like Buterin owns a corp or like some
bitcoiner versions of buterin are planning for such a position. Fuck 2nd layer solutions, improve the actual blockchain.
As of this proposal:
I think the idea of having some double referenced blocks called Superblocks here won't help with the canonical drawback of bigger blocks. When the number of transactions grows the propagation delay increases because nodes should query and validate the transactions and it affects proximity related problems.
For now ,I suppose it won't have support not because of devs being so fond of LN, (bitcoin is not Ethereum, nobody has conquered it, nobody dares to resist against a brilliant onchain scaling idea because of his corporate's best interests in 2nd layer solutions) rather because of having a parallel block just doesn't sound very different than suggesting an increased block size. I have to read it more deeply to be sure, tho.