Economically in terms of dollar size, China might surpass the US. In fact, it's quite surprising that they have not already, which speaks volumes in and of itself. For the most part, China is never going to dominate economically or politically. Currently, their economic development agencies are retarded, loaning money to ‘friends of the party’ instead of companies that are strong and companies with the potential of becoming strong. Currently, over 50% of government loans are not paid back and this has been going on for decades.
Additionally, China has seen double-digit growth for 30 years until very recently (last couple years). Any western country that experiences double-digit growth would be enjoying good times with an economy that is making all their citizens rich. Life would be totally awesome, and that is if a western country only experienced double-digit growth for just one year. But, China needs this double-digit development to just keep its head above the water. It needs to keep the containers filled and going to western countries to keep their factories running. To do this, it needs to keep their prices down or western countries would not accept their inferior products. They extent credit to these countries as well, again they need to do this, or western countries will not buy their products and their factories would not operate at current levels.
Most deals are consignment type deals with the west and China is always waiting on payment to pay its backers in Europe. Eventually, the Chinese people will not be able to absorb these transactions until payment, European backers will get frustrated and call in their makers. Eventually, the Chinese government will not be able to contain the people and civil strife will become the dominant focus of the government. To contain order, China will close its borders once again as it did in centuries past and to save face the government will blame the foreigners instead of recognizing mismanagement and accept blame.
The third world war (WWIII) will be between Japan and the US around 2050, with Japan once again attacking the US (in space) in a bid to obtain more resources. Japan will need to do business with the Eastern Chinese seaboard, who will be taxed heavily to support the rest of China, further adding to the strife in China. One can expect this turmoil to occur in China prior to 2030. Prior to this, one should expect the collapse of Russia totally, which there have been signs of for the past 5 years.