Boise St should be in the West division with its geography. I would do the divisions a bit differently, adding SMU instead of Hawaii to give TCU a travel partner.
Realistically, I don't expect a move to 12 by the MWC. Most likely the move is 9 or 10 because after that the league would start to become dilluted with regards to money, TV and Bowls. SMU would be a good travel partner for TCU and I'm surprised there isn't more talk of the Mustangs.
SMU? That's some dreaming... SMU is lucky to be in Conference USA. I think they'll like it there better than the WAC. As the school that had the dreaded "death penalty," I hope that SMU can use the better CUSA recruiting grounds and rebuild. It would be nice to see a program that has been down for so long to rebuild. (I guess you can see why I'm an Idaho fan!)
I think the MWC will wait on what TCU decides. If they say yes, they will invite them and Boise State. If they say no, they will invite Boise State and Fresno State. I really think that they won't look seriously at Hawaii. I think the original plan when they left the Mega-WAC was to reduce the travel costs and become more regional. Adding Hawaii would stretch them out further yet again. So, one of two things will happen: 1. TCU & Boise State. 2. Boise State & Fresno State.