Bonds/Notes/Bills issued by the Treasury have fixed rates - so yes, the interest rates will stay that low until the money is paid off.
The point that others have brought up is that if the US Government borrows an incredibly large amount of money and pushes up the Debt/GDP ratio, future, additional borrowing will become more expensive. But if today's borrowing is used efficiently, it should drive up GDP and reduce some of the need for future borrowing.
> Bonds/Notes/Bills issued by the Treasury have fixed rates - so yes, the interest rates will stay that low until the money is paid off.
TIPS aren't fixed rate, but I don't know what fraction of new US debt is TIPS.
More to the point, you're assuming that we won't have to roll-over that debt, which only happens if we're not running a deficit. Since we are for the forseeable future....
> I believe the "real" interest rate on TIPS is fixed - while the nominal rate fluctuates with CPI.
According to that reasoning, interest rates almost never change because they're typically a given premium to inflation.
We don't accept that reasoning because you repay what the note says, not the relationship between that number and some other number.
> Your second point is, of course, right on. But if we have to borrow $x, better to borrow it now at ~0% than later at (likely) >0% interest.
Umm, no. Borrowing now at 0% and rolling that over later to a new loan at 10% is not better than simply borrowing later at 10%.
Yes, borrowing now is better if you do something useful now with the money, something that you'd delay by borrowing later.
However, there's little evidence of that occurring. We're running up lots of debt on dumb spending. If you want to do some smart spending, take the money from dumb spending.
The point that others have brought up is that if the US Government borrows an incredibly large amount of money and pushes up the Debt/GDP ratio, future, additional borrowing will become more expensive. But if today's borrowing is used efficiently, it should drive up GDP and reduce some of the need for future borrowing.