While I'm no economist, this certainly does worry me, and the big question is exactly how problems might manifest themselves. Are we talking about massive inflation? That would imply that it makes sense to own land, but it's a bad idea to hold cash or other things that can easily loose their value like government bonds. Stocks of U.S. companies are harder to analyze, particularly when the big ones tend to be multinationals who are (hopefully) smart about hedging currency risks. The biggest wild card of all is the U.S. / China relationship. We've outsourced all kind of manufacturing to China, and it comes back in the form of cheap goods at Wal-Mart. More interestingly, the Chinese yuan is tied to the U.S. dollar, meaning that they're (currently) sinking along with us. If the Chinese unhooked their currency from the dollar, then the price of Chinese goods, in US dollars, could increase, which would throw everything about outsourcing out of whack.

Personally, I've been slowly increasing the diversity of my retirement portfolio. I'm planning to double the "international" portion of my holdings by the end of the year.