Despite Bitcoin primarily using miner signaling for consensus changes so far, miners don’t actually matter as much as users: https://en.bitcoin.it/wiki/Economic_majority

If the vast majority of users and services decided to switch to PoS tomorrow there’s absolutely nothing miners could do about it.

That said, I’m not saying it would be easy to get consensus for such a major change. Futures markets might be useful for determining how much support for a change there is.