In the medium-run the dollar value will go down (in 6/8 months). There's non way the USA could repay the debt. Brasil,Russia,India and China (the BRIC) want a group of currencies non only the dollar, to be the world currency. They don't want, for the future, to encrease their dependance on the dollar. In the future they will become (and the China is becoming now) more advanced economies, not only selling goods to the west.
And the american debt holders are afraid of the american debt becoming larger day by day.
So you should expect bat times for the american bond and the dollar (but good for your export and debt).