If the Pac-12 were to expand, I think the academic side is a big driver to get the presidents and chancellors on board. Only looking at the schools that have D1A football programs. Also only looking within the geographic footprint of mountain & pacific time zones + CO border states (we'll include TX in that and ignore that strip of OK panhandle). AAU and ARWU is what they care about on the academic side, because they're looking for research partnerships and the money they bring.
AAU Members within footprint:
Rice University
Texas A&M University
University of Kansas
University of Texas
University of Missouri (not in current footprint, but becomes so if expansion into Kansas or Oklahoma happens)
ARWU Top 100 universities:
#37 University of Texas
#100 Texas A&M
With the last round of expansion, CU brought an AAU member that is #34 on ARWU. Utah is #93 on ARWU.
I think the presidents and chancellors would approve an Oklahoma without hesitation if they came with a Kansas or Texas. The ideal for the Pac-12 if it ever went to 16 from a revenue and research perspective would be Kansas, Oklahoma, Texas and Missouri. You could swap out Mizzou for a TTU or Houston, though, and it would work out just fine.