What I believe, Bitcoin will not end the dollar's reign. No country wants to devalue its currency whether it's dollar or yuan. They will make Bitcoin an asset or commodity like Gold. I know people want to like it but this is true. Still, we want fiat to spend money not bitcoin. Bitcoin will compete with Gold, not with the dollar. They won't this happen as they will lose the superpower tag which I believe no country wants it. They are 2 countries that are competing right now USA and China and they will make sure that Bitcoin doesn't come their way. Also, normal people have no knowledge about Bitcoin, how it works. For them Fiat is everything.