The first kind of bankruptcy, Elon & his Saudi bros keep the company, and the banks lose like 50-90% of their loans.

The second kind of bankruptcy, the banks get all the servers and office chairs and sell them to either a new data-mining company or a recycler. This isn't very likely, because most of the value of Xitter is all the people who keep visiting, regardless of whether Elon knows how to monetize them.