Just make the debt dischargeable in bankruptcy, maybe with the additional caveat that universities have to approve all borrowers because the will banks have recourse to recover some percentage of their loss from university endowments.
Whole "Anti-American Studies" departments will blow away in the wind, as universities realize they will be on the hook for the future failures they are creating.
That is reasonable.
There are three successful models already in place of which I am aware:
HILLSDALE COLLEGE (Michigan)-- No federal loans allowed. The college has their own group of lenders through which students may borrow. Rates are lower than the national average and default rate is near zero because college actually teaches useful skills so graduates can pay back the loans. How novel!
BANK of NORTH DAKOTA (North Dakota)-- Bank is state owned and issues the majority of the student loans for colleges in the state. Borrowing is severely limited for "fluff" majors and students not making academic progress toward graduation. The philosophy is "You play, you pay". For that reason, default rates are again near 0%.
COLLEGE of the OZARKS (Missouri)-- Every student is expected to work a certain number of hours in lieu of their tuition. Because it is in a major vacation area, most students get placed in a job related to their major. This is actual work which earns you the right to study there. No loans = zero default and graduates in high demand.
Three highly successful models which, while very different, all work.