Expanding on my previous post due to some questions via email:
The "interest rate" channel of income is effectively zero and has been for nearly 5 years now. This has caused Billions of dollars lost in "opportunity" interest income. The effect of this, and on government taxation policy ("income" not being quite what it was, recent healthy tax receipts notwithstanding) is to shift taxation emphasis FROM income TO assets. The effects of this will be profound.
One more important point: The value of the dollar is intimately tied to soft and hard American power. If "goodwill" was an accounting line item with respect to the asset side of Government, it would reflect a massive number in the case of America. Owning American bonds and assets comes with a tacit guarantee of safety AND the possibility of American military security. Foreign demand for U.S. bonds will not decrease appreciably.