One thing to remember that the Pac-10 needs to have a unanimous vote to include a new member, and that is what kept Texas going to the Pac-10 around the demise of the SWC. The real issue regarding the vote is that teams, specifically the Northwest schools want to be in southern California every year or play either USC or UCLA every year. Those teams help season ticket sales and recruiting when they play on the road.
A Pac-16 would have been fine because the original Pac-8 members would play their seven game divisional schedule and that would include USC and UCLA every year. In a twelve team league that can not be guaranteed if there is a split by geography, and could cause the Northwest block to vote against adding a 12th member. The Colorado vote was unanimous most likely on the assumption of being in a division with UCLA and USC where nothing would change.
The addition of Colorado has been speculated could be the only move the Pac-10 makes, but I am not buying that. Just play along here, an eleven team league can only play an eight game schedule, because mathematical it is impossible to play nine conference games with eleven teams. 11 teams x 9 games = 99 ÷ 2 teams per game = 49.5 games, not going to work. A game against USC or UCLA in the same year is likely but there would be a year when both would be missed, maybe once a decade.
A geographical divide would look like this:
This set up makes geographical sense, but the Northwest schools would not like this that they would not play USC or UCLA on a consistent basis. In a nine game schedule the other division it would be once every four years that the other division would not play either USC or UCLA, but it would be less for when those schools would travel to the West division. One benefit to this is that rivals would not face each other in the title game.
Zipper division fixes this problem:
|Division One||Division Two|
In this division their would be a set rival in the opposite division -- similar to what the SEC has -- the five divisional games, and then three cross divisional games rotate. An eight game schedule could be the same with only three cross divisional games with one being their rival. This gives both divisions a chance to play in and play against a Los Angeles team. Having a presence in southern California has been a sticking point in expanding to twelve teams.
The problem with this set up is that rivals could play in the regular season and then in a title game. Besides that this could be a scenario that all teams might be willing to go along with. However, USC is a powerful beast and they help boost season ticket sales when they come into town.
The vote to add any team must be unanimous, and the main sticking point is a schedule that everyone likes. So, if Stanford or any of the northwestern schools object then Utah is out, but on the other side an eleven team league is not that great and a title game would bring in some of the money that the Pac-10 was trying to get by adding the Big XII South.
So, there is a shot that Utah could be rejected by the Pac-10, but money trumps all so expect Utah to get the votes.