Other pac-12 schools by offering them to keep more of their revenue and not have to share it equally like they do in the pac-12.
If Washington, UCLA and usc banded together then there is really not much quality difference between the left over 9 in pac and the leftover 8 in big 12 so they could basically get the 2 conferences in a bidding war. Add Oregon in with those 3 and those 4 teams could basically Name their price between big 12 and pac-12.