I don't know any percentage but the fact is that most students are not in college on athletic or academic scholarships and most students did not win an education.
Simply, most universities will lose most of their student population due to the cost of an education is too high.
Yet, reality, most universities can not afford to allow such to happen. If such happens, they will no longer be able to afford the salaries of professors, can't afford particular sports teams, can't afford particular university events and loss of scholastic rankings.
Therefore, what happens when education continues to increase ?
There will be this migration of the student population to other types of education and cost saving...such has already started.
I'm not talking about students leaving the U.S. to go to other countries although I will give an example of such in my P.S. statement. What I'm talking about is that there are more junior colleges offering more education alternatives including degrees that's competitive with traditional 4 year degrees because the junior college offered the same classes specific to the degree without the other requirements, more technical schools, more schools offering cheaper online education, more employers paying back their new hired employee student debts, more employers offering college tuition to the children of their employees, more students working full-time jobs while going to college part-time, more students joining the military to their costs payed for when they exit the military, more students from one state immediately establishing residency in another state so that after their first year of college...they than can establish themselves as an in-state student instead of an out of state student that pays tuition 2 to 3x higher and there's many other alternative education cost savings I have not mention.
Simply, parents and students need to make changes in their lifestyle if they want to be able to afford a traditional college education. Currently, most are unwilling but rising education costs have not reached a price that forces most to do so.
It's kind'uv like the things about oil/gas/automobiles. What price (how high) does gas need to get to force people in a mass number to use alternative transportation that is cheaper ?
I don't know that magic number but I do know that when oil reached its highs...it started conversations among my personal friends but nobody actually did anything. Seriously, I remember one friend said he may need to move nearer to his job, another said she may start car pooling, another said he may start riding motorcycle more often, another said he may buy a hybrid, another said he may have his kids go to school closer to home instead of that extra 30 minute drive each school day.
My point is that people adapt but only if the costs reach a point that forces that adaptation.
P.S. A friend of mine has dual citizenship in Canada (born in Canada) and the U.S while residing in the U.S. His birth right allows his daughter to attend college in Canada. The university cost in the U.S. is too high (University of Michigan) and his daughter made the decision to attend university near her grandparents in Canada...its extremely cheaper than the same education in the U.S.
Yet, she plans on attending graduate school in the U.S....hopefully on a scholarship (endowment). They adapted.