I don't think China will ever surpass the US, at least not in this century, that's for sure. Nor economically, nor military.
The Chinese economy is far too small. The US GDP in 2007 was 13,840,000 million USD, more than four times bigger than China's (only 3,280,000 million USD).
Yes, China has a very fast economic growth rate right now, but history shows that those rates slow down over time.







