redeeming debt does not increase total debt, therefore, no debt limit problem. so, no, you've got it wrong.
What you're saying is like this: I have balloon note of $10K due on my truck, but I will buy a new truck and owe $10K on that, so my total indebtedness will not rise. OK, but how do I pay off the the balloon note before I get my new truck without $10K?
Think cash flow, not total indebtedness: to get the cash to pay off the notes, the US would first _borrow_ the payoff amount, get it?