The four remaining Pac-12 schools, California, Stanford, Oregon State and Washington State, will have options if they are looking for another conference.
A group of Big Ten presidents has begun discussing the possibility of adding more West Coast schools to the conference if the Pac-12 continues to crumble.
Colorado's announcement Thursday that it will return to the Big 12 comes a little more than a year after USC and UCLA said they were ditching the Pac-12 to join the Big Ten.
The women's Pac-12 Conference Tournament gets underway Wednesday in Las Vegas with four first-round games. The conference has a chance to place at least eight teams in the NCAA Tournament.