There's some decent academic institutions in the Big 12. I don't see the Big 12 as a fit for Stanford. They have indicated a desire to get to 16 teams. Colorado makes 13, Arizona would be 14. I don't see Stanford/Cal as potential conference participants. Neither does this guy, who mentions nine potential candidates, none of which are either Cal or Stanford...but the top five candidates are all Pac-12 schools.
Ranking the Big 12 Expansion Candidates
Ranking the Big 12 Expansion Candidates
Audaces fortuna iuvat
