There's a strong possibility that the Dollar could drop in the long run. As US treasury bonds mature, holders of these securities like China and Japan, might need that cash to prop-up their own home economies as the fall-out from the global financial meltdown begins to bite.
I very much seriously doubt the Japanese will do that for both internal and external reasons. China - has lots of $$$ supposedly and they wouldn't want to devalue what they currently have either.