The question is skewed, China is already far more powerful than the US. They resemble what we use to stand for at the end of the industrial revolution. They have power in every form, its time we stepped back and let them just take their place as number one, we can't stop them.
The US economy is in decline. Some may argue that it is still steadily growing don't understand that the growth rates are declining with China's growth rate is increasing. Beyond that understanding, China builds stuff and sells it to the US. The US is finding it harder and harder to make things other countries want to buy. The service industry which was intended to replace the manufacturing industry is failing to produce the expected results.
I do not think that the rise of the Chinese economy means the decline of the American economy. I think that both economies are able to co-exist in a world where both are doing really well. I do think that the Chinese economy will not stay strong however. I think a lot of their numbers have been fabricated.
As the Chinese are one of the largest loaners to the U.S. It would only serve to strengthen us in the long run for their economy to rise. Also in tern, the Chinese economy would likely rise from the U.S. Economy rising. We only help each other in the long run.
The rise of the Chinese economy is simply the rise of the Chinese economy. The people there aren't doing nearly as the ordinary American is, and the Chinese economy, as a whole, is still only half that of the United States. Even if it passes the USA in GDP, this bubble will eventually burst because of American immigration and the massive aging Chinese population.