For better or worse, probably about the same as now. Ethereum's stakers have no more governance rights than miners, and their return on capital probably isn't better than miners' since the reward is so much lower.
Some other PoS systems use delegated proof of stake, where most people just delegate their stake to one of a small number of validating nodes, which could easily cooperate to censor transactions. Ethereum supports a very large number of nodes, due to signature aggregation. Right now there are about 400K individual nodes. Entities of course can have more than one node, but the last estimate I saw of the number of individual entities put it at around 5000. (That was at least six months ago.)