I have to admit I am curious to see what happens next. I never liked the idea of joining the Big 10, and while the Pac merger that was floated during all of the movement in the past seemed intriguing, I think it would have been a bad decision in hindsight.
I am fully in the camp of expanding the league and reducing the conference games. That would allow us to play the same sham game that the SEC does, where most of the good teams duck each other and pad their records feasting on the bottom half of the league and 4 OOC games. That would allow a team like Kansas to find 4 teams they can beat, and change their record from 2-10 to 5-7 or something close to it. The top teams can pad their resume and not all knock each other off, while having more flexibility to schedule other P5 teams.
I'm much less interested in the "who" mainly because I don't see teams like USC leaving the PAC or Arkansas leaving the SEC, even though it may be in their and the Big 12s best interest. Obviously, we should get the best teams possible, but I would rather look east than west.
To @Al_4_ISU point, I think the discord in the Big 12 stems mostly from the point that it is the only P5 conference that most of us were alive when it began. The fact that Nebraska was butt hurt from the beginning didn't help. But I think it is good that OU and Texas seem to want to stay in the Big 12. I don't think abandoning the center of the US to join an edge conference is in our best interest long term. We need to stake down the center and grow.
I was hopeful that CDC would help the Big 12 by focusing Texas and our admin on the health, growth and long term future of the Big 12. I am less optimistic based on current events, but hope I am reading that wrong. Regardless, there is something to be said about the passion and unity of the SEC and to a lesser extent, the Big 10. Those schools want to be together and it starts at the top. Texas and OU need to work to make the Big 12 a place to be. Arguing for an 8 team playoff that includes all P5 champions would seem to be the right place to start.
Call me crazy, but I would personally be fine with taking UCF, Cincinnati or others in that range out east. I was ok with the WVU add, but wished we had picked up Pitt or Louisville to make them a better fit. I think we would need to do the same if we added someone like UCF.
TL;DR - We should definitely look to grow and alter our model to avoid the round robin format that kills our top teams and makes our conference championship game a useless rematch.