First off China has what was supposed to be explosive growth for the last 20 years has only 4.33 trillion GDP compared to the U.S.'s 14.2 trillion. China's economy WILL slow down at some point. Politically the U.S. is still in control in global affairs and won't be dislodged as we see in Haiti only the U.S. can provide quick and effective aid and third world will continue to look up at the US. The US still has NATO and its allies in the EU, Japan, South Korea, Australia, and New Zealand. And no China will not become the #1 military power in 20 years. Their budget is just not large enough to fill the gap between them and the US in 20 years. And that's without the quality training which takes time especially for such a large military as China has.

China is definitely going to be much more influential in the coming decade as they say "money talks." But in no way is the U.S. going to surpassed anytime soon.