That is what caused the hold up the last round of Big 12 expansion, as OU looked at options and actively tried to join the PAC. Unfortunately for Oklahoma, the PAC told them the weren't interested in only Oklahoma but only if Texas came with them.
At this point, Oklahoma is somewhat stuck. The PAC said no, they don't quite have the academics for the Big 10 (not an AAU school). Also, with the SEC already at 14 they have less interest in expanding and it is unclear if they would take Oklahoma. It is also not clear Oklahoma would go to the SEC; while fans would like it, it doesn't mesh with the goals of the school as Oklahoma is trying to improve its academic ranking (part of why they wanted the PAC).