Well i don't think Ethereum's concept of proof of stake would make it a centralized network. By running a PoS protocol all that miners need to do is to get the required amount of collateral number of ETH needed to be a masternode. I think this is equally fair and i am sure staking would also be enabled so that other smaller miners can also join.

Ethereum's switch to PoS rather makes it a more decentralzed ecosystem.