What state is the most important to MWC recruiting? Texas or California? That might make the difference in expansion for MWC.
The MWC may hesitate taking any more teams from Texas, as that might take on the look of the old WAC-16, and what led them to break away to form the MWC. UTEP, Houston, SMU and Rice, all individually are still possible candidates, but I doubt they will ever become something that they were trying to move away from. Its not so much Texas per se, as it is any alignment that would hinder current core conference rivalries, such as CSU vs. AFA, Wyoming vs. CSU, Wyoming vs. AFA, Utah vs. BYU, BYU vs. anybody in the Mountain 6 core of the conference. No new alignment can disrupt the historical core of the conference, that is BYU, Utah, CSU, AFA, Wyoming, and UNM, perhaps SDSU. If any alignment tilts in a certain way that affects scheduling of core conference rivals, through divisional alignment or weird geography, the MWC will not go in that direction. That is what they are not the WAC anymore and why the MWC exists in the first place.
Fresno State may have all the elements for conference expansion (competitiveness, market, recruiting base of California, etc), but Boise State has had the best record and ranking and is the team of the moment.
Never will happen, but it would have been a fairly good conference.