People will attempt to run slashers against the regulated stakeholders because they're not doing their job right and just kind of hope that in a system that only works because wealthy people would refuse to lose money otherwise; that the wealthy people would be willing to lose money.
So the rich regulated forks will say fuck you and a fork will be the only solution that schisms the chain into a regulated fork where the rich people maintain a truth hat they've never done wrong and a non regulated fork where they have. People like off ramps to actual dollars so the regulated one will retain value while the other one drops rapidly. Stakeholders that think its cool to help people dodge sanctions will just lose their stakes by means of PoS because they're not maintaining "The Truth" in the regulated fork that they don't approve of and by declining market value in the fork that they do.
And in one glorious moment the PoS ecosystem will kick out all the decentralized dreamers
Even after the Tornado Cash sanctioning, people in the blockchain space designed simple mechanisms where validations can't censor transactions to/from specific entities because they won't know what any individual transaction does.
To meet your prediction, some rich group would need to launch their own network and make code changes to support the features they need. I think the wealthy who were going to do that would just start a private "smart contract" that can run code and make transactions on a centralized, non-blockchain system.
There's no reason they'd need to keep running a blockchain if they were going to centralize decision making.
This would have an impact on the price of the PoS coin, for sure, but it would still pale in comparison to the physical costs of trying to compete as a miner. Not just capital expenditures for hardware, but operating costs as well. Buying a PoS coin is all that one needs to do in comparison.
Coins that start without PoW have one entity holding 100% of supply that other people need to buy from them, leading to terrible wealth concentration.
ETH Mainnet is due to replace PoW by PoS by merging with Beacon Chain this September: https://ethereum.org/en/upgrades/merge/
Most L1 chains outside Bitcoin and Ethereum use PoS or variants of it.
For example Solana, Cardano, Polkadot, Polygon, Avalanche and NEAR all are proof-of-stake chains.
Ripple has another non-PoW mechanism too.
I think this is good.
Whether or not blockchain is a good thing, it's very clear that proof-of-stake is an adequate and energy efficient alternative.