most likely we will have to switch to Proof of Stake when the price approaches 5-10 million dollars and not a single ASIC will be able to work in such a way that it brings profit
ASIC profitability does not really have to do with price. If the price is high, then Bitcoin will have by definition a bigger security budget than if it stays low. So ASICs will work fine if the price keeps increasing.
The danger is of course lower price growth than the equation: "block rewards + transaction fees + merged mining rewards" decreases due to halvings.
If "merged mining + transaction fees" alone is enough for a solid security budget, then Bitcoin is probably fine for the long term. Even if this security budget is lower than now (2025) it could still be high enough.
Do you think Bitcoin was safe in mid 2016 for example? The security budget in August 2016 was only about 1,5% of the current security budget: we now have a block reward of more than 350,000$ (110,000$ * 3.125
BTC) , while back then it was 5000$ (400$ * 12,5
BTC, fees were negligible back then)
The mid-2016 value is approximately the security budget we would have if now magically all block rewards disappeared, as the transaction fees make up currently 1-2% of miners' income. . So a return to 2016 levels is very much the worst case what could happen in the late 21th century. I expect the fee level + merged mining however to be higher even in a pessimistic scenario, at least 10% of the current value.
but the question is different, is it possible to do this technically and transfer the blockchain to Proof of Stake? and who can do it?
Technically it is no problem, it has been many times in the altcoin world, including by the altcoin #2 called Ethereum if you remember

"Who can do it" is a trickier question.
On a first glance it takes only a developer to implement the PoS code, and then the "economic nodes" (exchanges etc.) would be those who decide if this update "is still Bitcoin".
But there could be a strong movement opposing this change, which could be led by the miners (because they would be deprived of their income) but also Bitcoin enthusiasts who think that PoW is the best and most decentralized method to secure the blockchain. Including myself for example although I'm a nobody so my opinion alone would not count anything. This movement could create a hard fork, and it could be stronger than Bitcoin Cash in 2017, i.e. really challenge the answer to the question "what is Bitcoin"?
For example, the PoW defender group could create a fork with a tail emission, to ensure the security budget stays solid. That would also have its opponents but if the budget is already quite low it could work to attract enough people. In this case we would have a competition for the title of the true Bitcoin.
Thus, if really PoS is thought to be the best solution, there should be ample consensus before such a change is decided. And I guess this option would only be really on the table if the other options (tail emission, merged mining etc.) are too unsafe.