Since your first point suggests that you're doing this after the fact for pre-existing student debt, an insuperable problem is that you can't legally execute most of your plan, as you'd be forcing parties to accept contractual terms that they may not want to accept.
You can't force the colleges to assume debt they never signed on for in the first place.
You can't cancel degrees of folks who don't pay their debts unless that was a pre-exiting contractual term between them and the college issuing the degree.
You can't attach the assets of a college or university for failure to pay a debt to the government they never voluntarily, contractually entered into in the first place.
This is something that could possibly be legally permissible moving forward, but there's already a trillion dollars worth of student debt, and your “plan” offers nothing to ameliorate that problem.
sitetest
Anything is possible under the law. Bankruptcy does all sorts of “contract cancellation” action, and see that the government has the power to force people to buy a product, as long as the law is styled or disguised as a tax.
Colleges who sell worthless degrees should get no more protection than used car dealers who sell lemons.