Can they? Sure anybody can sue anybody.
Will they? Absolutely not. Not one school has terminated their relationship with a shoe company after Adidas was named in the FBI case and Nike was subsequently raided by the FBI a week later (more fallout from that to come). I can't think of a single AD or school president that even criticized them publicly.
There's an economic ecosystem at work here that nobody (ADs, Coaches, shoe companies, etc.) wants to see go away —even the ones that don't cheat. Yes, they hate the cheating, but they love the money much more. Remember, before the age of schoolwide shoe contracts, assistant coaches weren't paid near as much as they are today. If "everybody knew" like so many former players and talking heads are saying, then there are a lot of people who weren't cheating but chose to look the other way too.