Maybe if they really want to D.R.E.A.M., they can apply for US citizenship. Then, if they are good students and seem to contribute to the future good of US society, we can grant them citizenship. But if they don't seem to be of outstanding promise - sorry, no $$$, no citizenship, no scholarship.
There is free state university education in all of Mexico --- instead of expecting the American taxpayers to give them a free ride, they can go home where their own government will provide it. They are being denied nothing --- they can go to college back home --- and it's free for them.