With regards to blocksize, the only reason it’s not widely embraced is because it’s known to directly impact propagation delay. One side couldn’t care less about centralization, the other side cares dearly. SegWit was activated, which compresses transaction size and doubles transactions per second without impacting propagation delay. Mimble Wimble and Schnorr signatures are coming soon, which are also soft forks and compress transaction size even further. There’s plenty of change happening that are all very intelligent scaling solutions. Big blocks are not intelligent nor difficult to implement.

There have even been successful atomic Bitcoin<->Litecoin cross-chain transactions with Lightning last month.

It doesn't matter - it can fork. And if the fork offers something compelling, it will get used. Even Bitcoin Cash, which is not (very) compelling, is now tradable more than most altcoins.