If I recall the Matt Levine newsletter correctly the banks have already discounted the debt so I would think they'd be happy to sell it for less than the original $ value, either to Musk or Musk associates.
As I mentioned, it's already down 40% last I saw. And they will take less, but they aren't going to give it away. One, it sets a bad precedence, and two it's bad business.
ML also mentioned he hoped Twitter would stiff the banks on the first interest payment like they have been doing all their other creditors. It would have been an entertaining game of chicken. The other unknown is if Elon really wants to dump more money into this, though he may feel pot committed. But what if he realizes there is no winning option?