I honestly don't think it'll happen, certainly not in 15 years... In 100 years maybe?
Yeah I also agree with it, bitcoin can't replace dollar for to short of time. But maybe in 100 years from now will see.
Yes, no strong support from big countries will make the future bitcoin difficult to survive for a long time, let alone to turn the dollar which is the world's strongest currency, I'm never sure bitcoin can replace dollar forever.