To be clear, they still have the GI Bill, which grants them a certain amount of cash per year. But that's a limited basis, and most people save that for A) add'l education when they get out of the military, B) topping up (ie. if you're going to a school where the credit hours are more than $250 per hr, you can use the GI Bill to pay the rest), or C) donating it to your spouse or children.
I plan on donating mine to my children... assuming they keep tuition assistance going. If not, not sure what I'll do. And obviously like you said DoK, this affects enlisted a ton more than officers, since officers already have a bachelor's degree.