Whether Bitcoin existed or not, the Dollar will end the Dollar's reign. 
Fiat currencies don't last forever. They can't. With all debt-based money, eventual failure is an integral part of the recipe. It's just how they function. Some last longer than others, but they will all approach worthless at some point.
Fiat currencies don't last forever. They can't. With all debt-based money, eventual failure is an integral part of the recipe. It's just how they function. Some last longer than others, but they will all approach worthless at some point.
More likely the Federal Reserve will end the Dollar's reign,by mass printing more dollars.
Anyway,the US dollar might not be a world's reserve currency after 10-20 years,but it will remain the national currency of USA,as long as USA continues to exist in the next centuries.
USA still has the strongest economy in the world,which means that the US dollar will still be very strong,even though it won't be a reserve currency for many central banks around the world..
and other counties are not fools who still accept the current exchange rate...