Don't know how much bias exists toward BYU.
About 1-1/2 years ago Larry Scott was asked about expansion (he constantly is). He considers anything west o fhte Rockies PAC footprint,
and he commented that the PAC presidents or AD's had discussed some possible FUTURE candidates.
He specifically mentioned San Diego State, Boise State, and I think maybe BYU (not sure).
There's a lot of bias. The LDS shifted the mission of the school back in the late 70's/early 80's, and took it off that PAC-like, and probably more damaging, UU-like, research-track mission. That's kind of been the shtick the PAC talking heads use when explaining BYU. It's not an institutional fit. It's private like USC and Stanford, but USC and Stanford are also AAU institutions, and BYU is not on that trajectory. Every other PAC school pretty much is, though, iirc (don't quite know of Oregon State and Wazzou). The change in institutional mission would have been forgivable...the LDS using BYU as a way to achieving certain political goals in west coast states? That's where the war really is between the Cal-4 and BYU.
I've long thought that part of the snub also had to do with LDS recruiting tactics. Because there are a lot of Mormons who play football on PAC schools, put BYU at the same level as some of those schools, and who knows how the LDS tries to coax those kids. In that regard, I don't know what BYU gives back to the PAC. It just sort of takes.
I think Utah State has a better shot at the PAC than BYU. To the PAC, they already extended an olive branch to the LDS...they took Utah. Utah State's in the same boat as UU...more favorable than BYU because of institutional mission, likeness, and a somewhat similar size.
Scott did mention Boise and SDSU. I think SDSU has a shot, albeit a very small one. They may get a rub if California politics get more involved, as the Cal State system is so large that to have the second-class citizen treatment of no PAC membership may make things a bit dicey. I think SDSU, while it adds nothing in terms of new territory, could be used as a way to reach other membership options where schools still get into California, if just not necessarily for the Cal-4. Boise's already a PAC member in wrestling...I think it goes to that extent and no further. I think Boise's 15 minutes are up, which is bittersweet.
If I had to rate the schools outside of Texas and Oklahoma and other Big XII programs that the PAC could potentially consider, I'd rate them:
2) Colorado State
3) Hawaii (a pretty big system all things considered)
4) Utah State
6) UNM or UNR
7) hell freezes over
8) still freezing
10) UNLV and Boise State
The problem for anyone outside of the top three is that if/when the PAC does expand again, I doubt they'll need any MWC additives beyond one or maybe two. Heck, if either the PAC or B1G wanted Texas territory so badly by now, Rice would be a member. Maybe #7 and #8 have better chances than 5-onward...