Came across this article and found this, which I had not heard anywhere else (FWIW):
The Big 12 schools signed an agreement to stay in the conference 10 years. If other things happen, it could be longer. Perkins says he has no reason to fear that any other Big 12 team will bolt on the league. All indications are that the teams are in the Big 12 for the long haul.
"Cliff's Notes version: Lew Perkins press conference, 6/16/2010" by The Newell Post / LJWorld.com
The Big 12 schools signed an agreement to stay in the conference 10 years. If other things happen, it could be longer. Perkins says he has no reason to fear that any other Big 12 team will bolt on the league. All indications are that the teams are in the Big 12 for the long haul.
"Cliff's Notes version: Lew Perkins press conference, 6/16/2010" by The Newell Post / LJWorld.com