Money talks and everything else walks. The ACC feared a loss of money by not expanding so they went to 12. Whats not to say the same situation could not play out again 10 years down the road that forces one of the BCS conferences to eat their brother? If TV money shifted back to the the Big East with Rutgers and UConn emerging as national powers whats to prevent the Big 10 or the ACC from grabbing more Big East teams especially in the case of the Big10 who needs just one more school for 12. Or would the BigXII slide in the power rankings, making the SEC look more attractive for Texas and TexasA&M.
Now going from 16 to 14 makes infinetly less sense. After Texas and Texas A&M, who else would provide more TV dollars for the SEC. Court MiamiFl and Florida St from the ACC? I don't think that would work. The Big 10 won't expand beyond 12 if they could get Notre Dame but if they go after Syracuse or Rutgers first for some reason I could see 14 there with ND eventually giving up. 16 in the Big 10 noway. The PAC-10 at this point is probably capped at 12 unless they try and bridge to Texas/TAMU.
As I see it, the big prizes out there to expand beyond 12 for a BCS conference are Texas/TAMU and Notre Dame. The Big XII is the most vulnerable out of the Big 5 because nobody in the PAC-10, Big10, SEC would be interested in leaving their conference to do 14 with the BigXII.
I would say that traditon, and the inability to play more than 12 games in a season, ala the fear of the WAC-16 failure also in an inhibitor to this scenario happening. I'm not saying that a whole new dynamic may not happen in the future that could impact all of college football alliances, but these forces can balance with money. Oklahoma and TTU are the achors for UT and A & M in the Big 12. Only Arkansas is the pull in the SEC direction because of a former long-term alliance. Sacrifincing Alabama/Tennessee rivalry just to get UT and A & M in the SEC or Alabama/Auburn seems a bit of a stretch.
As far as the Big 10. If the College football landscape does change and there is a movement to 16-team superconferences, and this happens either with the Rose Bowl gradually losing the tradition of Big 10/Pac 10, or a movement to a college football playoff, then 4 16-superconferences may come into existance where there is less emphasis on the conference, but more on the division, then you may see sweeping changes with college football alliances. This is a point where college football traditions are watered-down, and then global conference and divisional alignment happens across the board.