Troublesome Lagomorph said:
China basically owns the US. However, I don't see China having a good foundation for their economy and they're shit with politics. In other words: there are many, many factors in what makes a world power and since pretty much anything can happen. In other words: its really friggin hard to accurately predict this kind of stuff. For all we know, a couple of years from now the US will pull itself out of the hole its in and stop having to worry about being dethroned.
Two decades ago Japan owned the US. Before that it was Europe.
We're entering a brave new world where the US has to discover what Britain learned about a century ago: managing an empire is hard, and it can't last forever.
I strongly doubt China will ever amount to more than it already has, not to diminish it's gains, simply because it has far too many hurdles in the way. They have absurd scales of poverty to overcome when their rich are the US's middle class, and their poor aren't terribly unlike Africans making it day to day on pennies and nickles.
There's also the strong issue of political unrest, which I see only increasing as their GDP increases. People are simply dissatisfied with Chinese rule and it'll either cause something incredibly violent, or it'll be quiet and still undercut the country's economy.
There's also the general lack of respect for copyright protection and intellectual property.
In any case China's ability to project it's power is still living in the 1930's for any real application. Their navy is obsolete, their air force is still decades behind what the US is capable of, and they live in a region where any meaningful troop deployment is a logistical nightmare. It's mountains and mountains and more mountains.