I have yet to see anyone explain how increasing the blocksize increases centralization. It seems to be some idea that just took hold and that everyone believes in, because they believe in it.
And it doesn't end. There will always be a need for improvements because there will always be competitors ready to take over if we stagnate. stagnation is death.
Lightning requires segwit. Which is to say, it will be as worthless as segwit is.
Increasing the block size will require more storage, faster CPUs, and more network resources.
The further we go, the more we price out smaller miners and move mining to the cartels which is already a problem.
Congrats. It's now been explained to you.