If students attend classes online while living at home, then the costs go down dramatically. You are left with paying on an hourly basis for a tutor. When my daughter took the AP tests in Oklahoma, some of them were done in nearby churches. They can deliver test proctoring for cheap.
You can already get a respected online master's degree in computer science from Georgia Tech for around $10k. And you can do it at night, while working, eliminating opportunity costs.
This is incredibly cost-competitive with traditional schools. The elite schools will be fine, as they are essentially offering a private club for rich kids.
Other schools will not be sustainable. These dead universities will be great for remote workers, combining office space and housing in a nice walkable campus environment.