Might we be entering the expansion endgame?  God, let's hope so...

In a rapidly developing story that's strained institutional relationships more than 100 years old, Nebraska and Missouri have both said they are interested in moving to the Big Ten. If they leave, that might prompt six other Big 12 members, including Texas and Oklahoma, to consider a possible linkup with the Pac-10. The death of the Big 12 could put Kansas, Kansas State and Iowa State in danger of being left out of any major conference.

Source: 

http://sports.espn.go.com/ncaa/news/story?id=5262068