There's some talk on here of China's apparently inevitable rise and subsequent displacement of the U.S. as sole superpower. The media (and even some scholars) hyped this idea up a bit so it's understandable if you think it's reasonable ... despite the fact that it isn't.
The U.S. economy is still triple the size of the Chinese economy, and this simple fact masks immense disparities in, for example, per capita GDP (it is abysmally low for the Chinese). Also, the projected Chinese growth is just that: projected. In reality, the Chinese are in a dangerous situation where lots of civil unrest is liable to break out when economic growth slows, as it surely will. They currently have a housing bubble of their own, a huge amount of corruption, markets almost nobody in the outside world can access (making their future as a financial center ala NY or London dim), and a political system -- with a politburo of 9 or so people that think they can rule over more than a billion -- that no one is sure is compatible with the economic reforms that will be needed in the future.
On the military front, there is simply no competition to be had. The U.S. spends an extraordinary amount of money on procuring advanced weapons, on training and equipping its troops, and has a virtual monopoly on R&D. All of this results in the best military on earth, including a navy larger by tonnage than the rest of the world combined (with over 2,300 ships), including 11 aircraft carriers (China has approximately 0, and that is not slated to change anytime soon).
In short, China has an extraordinarily long way to go to usurp the U.S. as world superpower; its economy is only going to grow as projected with extremely optimistic assumptions and even if this occurs, it will be perhaps a century behind the U.S. when it comes to military capability and financial competence.