> what makes you think they'll stay open even if they weren't leaving?

The fact that their lender probably wants to squeeze any return they can out of it and they stand to lose far more money leaving it with lights off than at least letting it limp along until they can get someone else on the hook for it, to start.

It could be that the lender also writes off the loss and just shutters the mall, but usually properties in foreclosure stay open because they want to claw back as much make-up ROI as possible on an already down position.