Dollars are like any other commodity in the fact that if you have less demand and more supply, the value comes down. How many dollars have been spread thoughout the world through the IMF and World bank? Our currency has to be in a constant state of expansion, when that stops, were screwed.
One way to ameliorate the problem is to get foreigners to use the dollar in transactions between themselves. They already do that to a significant extent, but the introduction of the euro has reduced that practice to some degree. Now that they have so many dollars, and the euro is less available, maybe that will change. They've either got to use those dollars, hold them, or unload them. The first choice may be the most appealing.