"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.
When it comes to price then there's no way that we could really be able to guess on where it would really be ending up but since Bitcoin would really be more scarce on the next halving and so forth
and if the demand and recognition would really be gradually increasing then we can assume out that the value would really be increasing also and there's no doubt with that. We do know that
it would be always depending on the demand and supply when it comes or speaking about value on which we are talking 6 years from now which there's still so much things that could happen.
We dont know if institutional funds would be flowing more into crypto space even more or would really be having that kind of ETF bad impact or its cons. This is why
there's no way that we could really be able to predict on whats ahead because there would really be several factors on which it could really be able to make out such impact
in regarding value or price on which we know that this is something that cant be known.