Given how hard it is to agree on a minor and obviously beneficial block size increase to 8 or 20MB, I doubt such a large and destructive change to increase 21M cap can have any chance to happen. Ever.
Why wouldn't miners support an increase in cap? If they can keep mining 25 coins instead of 12.5, ofcourse they are in! Price won't be cut in half, so they win out..
Because that would lead to inflation, which reduces the value of each coin. They might get more coins, but each coin would be worth less. You have no way of guaranteeing that the price wouldn't be cut in half, or worse. If enough people dumped their coins and jumped ship because they don't approve of that change, it's not beyond the realm of possibility that Bitcoin could return to sub $1 prices. But again, it's barely even possible that enough people would support that change for even the slightest chance of it actually happening. So it's not an issue. And also to reiterate again, attempting to tie this highly unlikely scenario to what's currently happening with XT is baseless and unwarranted.