But, at the moment, the college loan industry is doing NOTHING to share the costs. The colleges get to continue jacking up tuition far beyond the rate of inflation and the loan industry continues to enjoy taxpayer protection and better than market rate interest on loans which would never be made otherwise.
Changing the rules of the game going forward, for loans not yet written, for students not yet in college, is different (and acceptable and probably necessary) than changing the rules of the game AFTER THE FACT, and changing the contractual obligations on existing debt, especially, encumbering institutions with debt obligations that never legally signed on for those debts.
Some of your ideas might be starting points for a way forward for the future, but they can't be constitutionally-applied to the existing trillion dollars worth of student debt already out there.
sitetest
The problem is that the loan industry didn't make the rules. That was idiots in government. And they didn't borrow the money. That was the students and their enabling parents. I do believe student loans should be bankruptible - of course that will make them much harder for most folks to obtain, but c'est la vie.
An intact family can see that their child gets a degree cheaply. Maybe not in four years, and some may not be able to avoid debt entirely. But degrees are available cheaply to people willing to put in the work for them.
I live in Pennsylvania which has one of the highest state subsidized school tuitions (Penn State) in the country. If kids here can obtain cheap degrees, it can be done anywhere.