There is no such thing as a free lunch. The concept of a free college education is a noble one but someone has to pay for it. Given the partisan gridlock permeating throughout the US, this isn't going to happen. Instead of being idealistic, we need to be realistic if we want to tackle this challenge. There is one realistic way to decrease the cost of college by 25% - make the college degree a three year process instead of four.
What we need to ask is: What is the purpose of a college degree? To make you a better rounded individual, or to prepare you for jobs that require specialized skills? Ideally both. However, if you have to choose one or the other, then I think most people would choose the latter. Besides, isn't high school supposed to make you a well rounded individual? After all, not everybody is going to go to college.
When I went to college I was required to take art, literature and history classes, even though I was majoring in economics. I had already taken art, literature and history in high school which I enjoyed but I didn't want to pursue any further. Why was I forced to take these again? Given how expensive college has become this is a luxury we can no longer afford. Again, that is what high school is for.
So the idea is to cut out the general "liberal education" courses and only take courses that are directly related to your major. Your first year, you would pick two majors you find interesting and only take basic 101 courses related to those majors. This way, after your first year, you still have some flexibility in terms of what you want to specialize in. By your second year, you will know which major you like more and declare that as your real major, and relegate the other one to your minor (or if you like both then get a double major). And you would graduate after your third year.
The other advantage to this is that students will be able to start working one year sooner which means they will earn more over their working life. In addition, it will allow students to begin paying off their student loans one year sooner, thus minimizing accrued interest on those loans.