But it's not at all apparent that they're superior to the ACC/what the ACC is capable of (Notre Dame, Clemson, FSU, Miami have the cachet of Ohio State, Michigan, Penn State and Wisconsin). Similarly, no could stop USC and almost no one could stop Oregon when they were rolling.
USC/UCLA/Oregon could definitely bolt, but I don't think it's a foregone conclusion. The B1G isn't better, they just have a better contract right now.