The US dollar is world’s reserve currency for no reason, since after the Nixon shock it’s been unpegged from gold. As de Gaulle pointed out, for the rest of the world a dollar costs a dollar in goods and services, whereas to the US it only costs a few cents to print one. Countries have realized it and have been trying to bypass the dollar. Sadam started selling oil for Euros, quite successfully. Gaddafi wanted to introduce the gold Dina and sell oil for gold. And now Iran has set up an exchange in which it accepts other currencies. The Bricks set up the Bricks Banks and the Yuan is gaining recognition. What I am trying to arrive at is that if China can not retaliate in any way to protectionist American policies by intensifying bilateral agreements to bypass the dollar, with Russia for instance or by any other means. Moreover you may argue that certain products, shoes for instance, produced in the US would not be competitive outside the country due to high labour costs etc (although I know you were talking about the US internal market above).