It is possible that China will rise, but unlikely that it will claim the top spot alone. The U.S. has many allies that are unlikely to leave us. The problem, as I see it, is that both the U.S. and much of Europe are racing toward economic collapse to maintain social welfare systems based on income redistribution. China, while not having nearly our standard of living, does have a fast growing economy, but no desire to share that wealth with its masses (thus keeping a big export market), even if most of its economy is based on only producing cheaper clones of the inventions of others. Military power alone does not make a nation into a superpower, it requires both economic might and strong allies to remain on top. I do not see any nations teaming with China to push it into the top spot, certainly not Japan, India or Russia, its closest and most powerful neighbors. I don't see the middle east or southeast Asia stabilizing enough to be counted on as anyone's ally.