They of course cannot sustain that sort of growth do to structural economic and social challenges and ever growing Geo-political pressure - they cannot maintain the dollar pegging and the market restrictions for very long. Yes, they have more "structural depth" than Japan had as it came up in the world, but they also are up to a lot more questionable shenanigans. In the near to mid term, I feel that China's economic clout is exaggerated considerably. Long term - meaning out two or three generations - it is probably not taken seriously enough.
That is not to say that our policies with China in almost every area are not in shambles. Certainly we need much reform here. I do think that the Bush Administration is weak in this area.
do=due
But I don't discount things like the massive growth in raw material imports that China is seeing -- numbers in excess of 30% in one year are just incredible. China is now the world leader in raw steel -- in fact, they produce more than the E.U. does, and more than all of North America (well, that's mostly us since Canada isn't all that large of a producer of raw steel.)
If this were some vigorous young democracy, that would be one thing. But this is a totalitarian regime, and that's just not good in my estimation.
(If one did use such a measure of comparing exports/GDP, then let's see, our exports for both goods and services are a bit over 1 trillion dollars, and our imports are a bit over 1.5 trillion. So that's something over 2.5 trillion dollars compared to China's 1 trillion dollars, or 40% of our number. Taking an 11 trillion dollar GDP for the U.S., assuming that we could just apply that 40% to match GDPs would give China a 4.4 trillion economy. (If only the world were that easy! ;-) )