The PAC-12, like the BIG-10, is made up mostly of members of the Association of American Universities, and all are graduate research universities. As good as BYU is, its primarily an undergraduate institution. Plus the University of Utah doesn't want to split the small Utah market with BYU.

The BIG-10 is looking for large TV markets to expand into; its not going to ask Kansas or Iowa State which qualify academically. Plus Iowa doesn't want to compete in the BIG-10 with Iowa State, (which also is too far from any other ACC school to get invited there).

Also, there is no way that any PAC-12 university president) is going to agree to leave the academically prestigious PAC-12 for the BIG-12.

I agree that Texas and Oklahoma could leave the BIG-12 for the SEC. The then lower prestige BIG-12 then would look to add a couple schools; since they already have TCU (Disciples of Christ) and Baylor (Southern Baptist), I don't think they'd object to another conservative, religious institution like BYU. They might also consider San Diego State (large San Diego market and an up and coming program in football, basketball and baseball) and UNLV.