One way to make college affordable would be to exempt federal income taxes on the income of college graduates (assuming they can find jobs) until they have paid off their school loans. The minimum monthly payment on the loan would then be equivalent to the federal income taxes they would owe if they did not have a school loan to repay. When their college loans were repaid, then the employees would commence paying federal income taxes.
Students and colleges would benefit and the government and our society would more than make-up for the lost tax revenue after the school loan had been repaid. The colleges and states would not lose revenue, since it is the federal government that would forgo the federal income taxes while the student loan was repaid.