Well, I argued last year that our government will stop spending one way or another, and that the only question to be answered was who'll be in charge during: us or the rest of the world.
Now that question has been answered: the rest of the world will not tie their financial wagon to the American weak horse.
The only source of borrowing for the Treasury is now (and has been for awhile) the federal reserve (which despite the name is a privately owned and operated endeavor). The problem is, just like government, they cannot create wealth; all they can do is fabricate money. Contrary to what the vast unwashed believe, money does not equal wealth.
Do a little research on the Weimar Republic, and marvel at the parallels.