Euope is in trouble, US is in trouble. China has the largest foreign currency reserve atm. If China doesn't fall for the temptation of being and doing things excessively and they keep their economy growing as such and able to control corruption I must say they are in a very good position to be the world's only superpower in 30-40 year time with livelihood(and the decline in quality of life) in much of Europe and US becoming harder or much harder than they have been in past 20 year. US could become another Greece in the America continent.
As it is their money brings them a lot of respect from both US and Europe. They can no longer be perceived as just another state.