If you think #bitcoin is centralized in terms of mining now, this is nothing compared to what it can be when you add large blocks.
you need to realise an ASIC does not contain a hard drive. it does not store the blockchain or validate transactions.
ASICS are just handed a hash and a taget to hit.. (less than a kilobyte of data)
it doesnt matter if blocks are 1mb or 1000000000000000terrabytes.. the hash a ASIC receives is the same length.
meaning no cost to ASICS.
... sorry to burst that bubble of yours