That might be, but I think there is pop potential as people become more aware of how the "returns to college" are distributed. Essentially, only the best students in a handful of STEM fields have positive returns to college, but their returns are large enough to drive the average up pretty high.

It's true that colleges could scale down their expenditures to make expected returns positive for more students, but that would entail a lot of people losing their jobs. Major reallocations in the economy are what "busts" are made of.

Of course, I've been waiting for this bubble to pop for a long time and at best it's slowly deflating.