"Bitcoin mining will become unprofitable."
This one cannot happen. If mining is not profitable, then the network will not be secure, so activity and fees will need to be high enough to cover mining costs. If BTC goes fully mainstream mining will still be very profitable.
And I think mining manufactures will have to adjust, that's how they are doing it for years after the halving, they come with a better PoW machine so secure the network so it will still be as profitable as like two halving years ago. And most likely they are producing machines or design ASIC that can be cheap and cost effective and friendly.
Probably the OP is talking about the price, and again, very hard to predict but I guess Bitcoin will still continue to dominate the market, and be around 6 digits by that time and maybe more countries are going to legally adopt it like what El Salvador is doing.