China would not be left holding the bag at all. U.S. corporations have invested huge sums of money in China in the form of factories etc etc. Should we default, china will merely take possession with the stroke of a pen. The rest of the world would still buy their "American" products, made in China.
in bybone days a country would never let things like this happen. much 'imperialism' in the 17 and 18th centuries was merely a european nation trying to make another nation make good on its obligations, or make it relinquish 'stolen' corporations.