In my opinion, the US will remain the world leader. The US has the most developed army, and it controls NATO
At the moment, having military strength and money doesn't really make a nation a superpower. Allies are very important as well and with that the USA have a lot of allies and because of that enemies are always afraid to attack them. Russia and China who have the potential to become superpowers at the moment don't have a lot of allies.
At that moment Russia has not any potential to become superpower - weak economy, poor demography, only propaganda dreams and nuclear bomb. China all history was only regional leader and it doesn't seems that now something will change. So if not USA than only EU may be superpower, IMHO.