I'm not sure it's even worth a debate in USA anymore. Ban them or not, there's so many guns in circulation either way that it's never going to be hard to get hold of one of you really want one. Also, schools and colleges are rather public places, so unless you have a high level security operation at every place of education, which isn't feasible, then people are gonna have no bother getting guns in. I don't think labelling somewhere a "gun free zone" would make a difference.
I think it's madness they let citizens have guns in the first place but I think it's way too late to undo it. That's the sad reality. They should never allowed so many legal guns into circulation. You're never gonna recover then all if the law changes and you'll just have a lot of people selling them illegally.