I think people are underestimating the political issues associated with a breakaway. If schools start paying players and continue paying coaches millions, somebody in Washington is going to start talking about taxing athletic departments. It is inevitable.
People have brought up the first split in the 70s as an analogy. When the first split happened in the 70s, the Ivies didn't want to compete and voluntarily moved down. That is not the case today. Many Public schools want to be included.
Think about this. There are 15 states without a P5 school. That is 30 senators. Throw in the liberal states without a public school in the P5: Massachusetts and New York. And, how do you exlude the military academies? Also, you need to look at states that could have large publics excluded that want to be included which includes Florida (UCF, USF, FIU, FAU), Texas ( Houston, UTEP, UTSA), Ohio (Cincinnati), California (SD St., Fresno St.), ... And you have a large number of politicians who don't won't to upset a large number of alums.
Plus, if you start paying 85 men, then you have to start paying 85 women, which means women's sports at every university outside of the P5 will not be competitive for playes with the P5 schools. That impacts a large number of schools in many different sports.