>Are you willing to provide a more sophisticated explanation for USD demand? The biggest thing missing from my explanation is demand as an investment, or foreign demand to hedge risk. Which right now isn't huge, given interest rates are at 0.

Not who you're replying to, but I don't think you can have a reasonably complete explanation of USD demand without mentioning the petrodollar system/international dollar trade settlement. And how a number of countries are looking at ways to break out of that. Also, foreign dollar-denominated debt and debt service.