You're right, however things can take a long time to run out of steam. Also, it's very interesting how much of economics relies on everyone believing in the system.

I'd recommend checking this video out: http://www.youtube.com/watch?v=BH9YPtk5VB4. This is what many people think. While some can definitely brush it off, many aren't.

Well the US is exporting its debt (counterintuitive as that sounds) overseas by buying goods made abroad.

If I recall correctly 40% of US currency is actually outside the country.