Aside from whether PoS is better than PoW in terms of environmental, security or decentralization, the fact is Bitcoin community most likely won't agree with big changes.
Even block size increase, SegWit and LN which are "less controversial" have hard time accepted by the community.
And this may result in a big problem for BTC later. For technical reasons (payment ?!) and also my main topic:
Think of new "green" european parlament says: POW Crypto use are forbidden in europe.
They stop normal lamps for energy saving, even vacuum cleaner are not allowed to sell with more then 1000 W because of energy consumption.
They stop much plastic one use material starting 2020
And that was made under mainly conservative leading parlament ....