Could Bitcoin switch to PoS like Ethereum? That would also cause Bitcoin’s price to fall.
Have you thought about why since the creation of ethereum and as a number one leading altcoin it has not done so greatly proportionate to the number of years it has existed. Simple, it due to its POS nature, and a switch by bitcoin from POW to POS (which I don't see it happening) would mean that bitcoin will lose its independent status and value to which other cryptocurrencies follow suit at every moves it makes and become like every other cryptocurrencies. I understand your fears and it's mutual for some of us that care much about the future of bitcoin. However, I am optimistic that bitcoin won't lose it thrust to becoming POS, it's just not possible.
There's a reason why the current tech of btc is still popular today. And switching it to another tech would not guarantee that it would sustain its popularity of usage. But of course, we can't say that this can survive in the coming years. Remember, every tech has its expiration. So we will see how things will evolve in terms of this type of tech.