For all the hand-wringing, the current federal student loan system (under Obama's PAY-E program) has pretty sensible repayment terms. You pay a maximum of 10% of your earnings above 150% of the household poverty level (but no more than you would under an ordinary 10 year repayment plan), capitalized interest capped (over the lifetime of the loan) at 10% of the original principal, balance forgiven after 20 years.
It's progressive, there's a safety net, and it is, for the time being, solvent (government makes 30-50% profit on each dollar lent). Yes, people with great credit who would end up paying less under a standard 10 year repayment at say 5% end up subsidizing those who graduate without getting a decent job, but I think that's uniquely justifiable in this context, because everyone involved is turning to the student loans as a way to better their economic situation (after all, nothing stops you from paying in cash or getting a private loan at 5% if you can qualify for one).
I think if you added a cap in there instead of going up to full cost of attendance, to force schools to moderate their tuitions, it would be nearly perfect.