I’m not suggesting a bunker-type mentality, but at least being a little more aware, and having campus security keeping a closer eye on things, and at least realize that the threat is there.
A bunker-type mentality, however, is the only thing that would realistically be effective in preventing a motivated terrorist attack on a university. Sneaking some guns on campus would be very easy unless the schools are on perpetual lockdown and the terrorists could just go room to room and shoot.
The same goes for shopping malls, movie theaters, parks and anywhere else where people gather.