They might. This isn't the cold war; ESPN doesn't need Fox to die. Both sides just want to make more money.
So BOTH sides want the prime content (teams) from the ACC. Better to get some than none, and if the only way to get it is to split it...
Also, I think there could easily be schools that are more valuable to one conference/network than the other, especially considering how the BTN revenue model is so influenced by cable market access. Georgia Tech e.g. is probably about worthless to the SEC, but would have some decent value to the B1G.
Why would ESPN let Fox have schools they have locked up in an iron clad agreement which they control at a bargain price, to bet on a possible future outcome that they will not have control of and is just speculation?