I suppose that if ever there was a good time to run trillion-dollar deficits forever, this might be it. Of course, that all depends on whether the Treasury can roll all of its debt over into longer maturities before rates shoot back up…
Why are rates so low? John Mueller argues that interest rates are being driven down because of the Dollar's status as a reserve currency; something like $4 trillion is being held by other nations not to pay for our exports, but to stabilize their own currencies. This creates a serious problem, driving inflation and causing interest rates to decouple from fiscal and monetary policy. In short, politicians no longer suffer automatic consequences from borrowing loads of money.
Worse, if we were to stop borrowing so heavily, all it would do is to drive interest rates even lower as foreign buyers bid up the diminishing stock of Treasury bonds remaining. Eventually, the temptation of free money would grow intolerable to any responsible politician, and we'd start overspending again.
What can be done about this? Mueller suggests going back to gold as an international reserve. Short of that, I'm not sure how we solve the problem. Assuming that it is a problem to be solved.