You're already seeing ESPN lowball the PAC with the idea that they can just get Big 12 if the PAC deal doesn't happen. But if they do get the PAC and fill those late night slots, then the Big 12 has nothing left to them besides the leftovers from B1G's Fox.
That means a lot on ESPN+ and FS1; which is...not great... for exposure and money. Both these conferences are in a rough spot. The ACC would also be except that they aren't at the negotiating table.