How do you establish that root of trust with PoS? Currently approaches are ultimately circular, IE trust it because the majority holders of the coin are continually voting to trust it.
With Bitcoin mining pools it looks like there's just as much centralization (if not more) as with proof of stake.
US dollar payments aren’t subject to the approval of stakers, and existing PoW miners have no on-chain mechanism to prevent new market entrants from competing against them for hashrate.
So, “no”.
To begin staking, you first need stake. But merely transfering a PoS coin from an exchange to your own wallet for subsequent staking is inherently impossible without the approval of existing stakers. Even this isn’t enough: existing stakers must also approve of your initial staking transactions.
Which is not how PoW mining works.
So it's fair to say that Bitcoin could never "transition" to PoS since the whole premise from the start was that it wasn't! It could not exist before. Now that it exist, and has been shown to work, it has caused a cambrian explosion of sorts of protocols with less reliance on trustlessness. But they solve a different problem.
Your answer would have fitted well with the thread that responded to my question!
As difficult as the vulnerabilities of PoS are to solve, at least there's nothing yet to say that they can't be solved given enough work; wheras, from what everyone is saying, the energy problem is essential to PoW as such?