2nd layer scaling solutions are inherently vulnerable to centralization
It is important to have the same definitions in mind when discussing things like centralization...
... What's left is perceived centralization, however, cause such a network would tend to center around hubs with the biggest liquidity and connections, so it would look like hub-and-spoke topology.
It's a bit offtopic here though.
Indeed it is. But generally, I think there is no decentralized, trustless, secure solution in the horizon other than blockchain and I don't believe in LN being an alternative technology. Why should we use blockchain for LN by the way. One could adopt LN to be run on fiat and traditional banking system.
Anyway, you are the one who has come with an onchain scaling proposal and at the same time you are promoting LN?! Why should anybody even care about onchain solutions if he is a believer in LN or any 2nd layer alternative?
because of having a parallel block just doesn't sound very different than suggesting an increased block size
Very different. One is a hard fork resulting in a network split, the other one is a soft fork, not affecting legacy software in the slightest. That's the whole point.
So it is a block size increase solution without a need for a hard fork. But as far as I understand, the main controversial issue with block size increase proposals is not their need for a hard fork rather it is their centralization implications because of progress and proximity consequences.