the logical conf is the PAC-12, but they made clear their view of BYU when they invited the yewts. Anybody who knows a anything about college football knows BYU would've been the better program, even though plenty of idiot yewts may think otherwise.
The Big 12 came once and it didn't work - I don't know if it was BYU that screwed up that deal, the B12, or both - and they have little incentive to expand at this point. If and when the B12 expands, I think they go east instead of west.
So, as much as we'd like TH to work a miracle, I just don't think he can. He's limited in his ability, and in BYU being BYU (and I don't mean that as a dig against BYU).