We must be realistic, dollar is the strongest currency of the world and dominated by USA superpower. of course they will do everything they can to keep it number one, bitcoin is hard to replace the dollar.
Correct dollar is a most powerful currency in this world and i do not think bitcoin will replaced it, but it is possible that bitcoin would be one of the good currency in the future because of the big value of it and there is no fiat will replace by bitcoin it is just an additional currency can be used by all people in the world.