Testing a new way to fund a college education

I have thought for years that the most logical way for students to pay for college would be to have them commit to repaying a certain % of the future income.  Such a plan has now been proposed for the state of Oregon:

Oregon's legislature is moving ahead with a plan to enable students to attend state schools with no money down. In return, under one proposal, the students would agree to pay into a special fund 3% of their salaries annually for 24 years...

Oregon's plan has parallels to income-based repayment models used for decades in the U.K. and Australia, and more recently in the U.S., in which borrowers pay government lenders a share of their incomes to cover education loans...

In the 2010-11 school year, there were about 21,000 first-year students in public state colleges and universities in Oregon paying $171 million in tuition. To move them, and the next 23 classes behind them, into this program would cost the state more than $9 billion over 24 years until enough students had graduated and were paying into the system to cover its outlays...

The idea was first presented to Oregon legislators by students from Portland State University last year. Tracy Gibbs, one of the students, said that by freeing graduates from the steep overhang of debt many now face, the plan would allow young people to buy houses and contribute to their retirement accounts.

What the plan doesn't address, of course, is the inordinate cost of college.  That's a whole different problem.