Like you mention it'd simply create an equilibrium. People would declare bankruptcy when the discomfort of repaying the loans exceeded the discomfort of declaring bankruptcy. If I lend you an unsecured $10 which you then expend on something personal and materially intangible (such as an education) you're not going to declare bankruptcy to get rid of that $10 debt. If I lend you an unsecured $1,000,000, you almost certainly would declare bankruptcy to get rid of that debt. So we can say that my risk (as a lender) in lending you $10 would be 0%, while my risk in lending you $1,000,000 would be 100%. There's some curve there where I maximize my profit:risk in the middle that depends on the specifics. Like any loan it now becomes the job of the lender to assess that risk, determine eligibility, and profit off sound financial decisions - or, themselves, go bankrupt with poor financial decisions.
I think this would be a vastly better scenario simply because all interests would be aligned. Universities would have an incentive to keep prices reasonable because lenders would want to keep the total amount lent per individual relatively low. Universities would also have an incentive to ensure students would be likely to be able to comfortably provide for themselves after graduation because, once again, lenders would have an incentive to ensure that the people they're lending to will be able to comfortably pay back their loan once they graduate. And so forth and so on. In the end, we'd likely reach a scenario where it'd be relatively easy to obtain loans for majors likely to improve your ability to comfortably provide for yourself, and relatively difficult to obtain loans for majors likely to leave you with difficulties providing for yourself.
A world where anyone could pursue education, on public dollar, on any topic they'd like, is an interesting idea. I look forward to seeing the outcomes now that such systems are truly starting to be put to the test. Many nations are facing substantial pressures on their social systems such as aging populations, increasing costs of medical care, reduced fertility rates, immigration of lower earning individuals, etc. At the same time, the face of the job market is constantly changing such that an ever larger share of all desirable careers require some degree of educational specialization to even get your foot in the door. These are relatively new problems and I'm not entirely convinced that utopic ideas of decades past will remain viable in the decades to come - though I certainly hope to be proven wrong!