If China gains 'complete economic ascendancy and preeminence', it will be in the far future - not near. China is in a very precarious economic state. 50% of their economy is trade; 40% of their economy is the internal economy that is generated from the funds from trade. Without trade, the Chinese economy collapses. However, China is no longer the cheapest place to manufacture goods, and their need for resources is exceptionally high - resources that they must import. Things could easily become very bad for China economically, and they know it.
Watch what China is doing. Leveling the power gap by buying American debt. Reaching out to the developing world to build infrastructure (e.g. building high-quality roads in Africa). China is out to make friends in the developing world and ensure that the developed world can't afford to make China an enemy. Dominance is not the end game. The goal is to make the rest of the world as dependent on China as China is on the rest of the world.