I'm a little new at the hole cryptocurrency movement but do i think it will ever replace the doller no maybe smaller countries might try it but it still has to be backed by something i would think. As far as the US using to replace the doller what power would they have using it or power over other countries. The US would definitely have to have there own so they can control its value in that case they would destroy its value in the long run like everything else. Gold and silver at the end.