TCU would never join the Big 12 and Texas would never want them anyway. There really are no benefits for TCU to go into an already overcrowded Texas (big 12) conference. Even if they did, it would depend on what other college they got to come in before they decided if OU would go North or not. OSU would be 1st, but if they got another North college, would they break that rival or not and be lopsided like the big 10 is now with the geographic.