With the Big Ten up to 20 and the SEC landing their preferred candidates to get to 16, the Pac-12 and UT would have to make a deal.
The reality is that there would not be a way to make either the PAC or the Big 12 into a top revenue conference with both conferences keeping their current membership.
The Big 12 is the lesser conference. It would have to go.
It would take a vote of 8 of 10 members to kill the Big 12. In theory, the basis would be the old PAC deal for 16 (UT, Tech, OU, OSU) plus 3-4 more candidates.
Obviously the PAC-12 was prepared to add Kansas as A&M's replacement in their first push for 16, so Kansas is in as the fifth Big 12 school.
I think the A&M departure did a ton to further open Texas recruiting to SEC schools. Dallas/Ft. Worth is a key recruiting territory for UT & OU --- not to mention Tech and OSU. I believe the four felt they absolutely had to add the best "home school" in DFW to remain the "home conference" in DFW and as such protect their recruiting turf.
The four could not afford to see the SEC figure it out and add TCU. OU and UT do not want to see TCU vs. Arkansas or LSU in the Jerry Dome each year fueling SEC recruiting in DFW.
I think this situation would still be potentially in play if TCU was left behind for the SEC, so the PAC would have no choice but to bring them along for the ride.
Now some might think there is no way the PAC would admit a school with religious connections. I do not think that is the case. The evidence that would be presented against my contention is the PAC's balking on Baylor and BYU.
Let's start with the big PAC headache, BYU.
BYU made the institutional choice most religious privates have made, not to heavily pursue research. The PAC-12 and Big Ten have a conference culture that strongly values research. BYU specifically limits research for religious reasons. Regardless of how strong BYU's undergraduate program is, that combo will not fly in the PAC unless all of the PAC's other options are exhausted.
Plus BYU won't play on Sunday, which is an annoyance.
Plus a lot of liberal leaders in the California schools resent the hell out of the LDS church for bringing their money across state lines into California to fund the opposition of the California initiative to legalize gay marriage in California. This appeared to be the LDS church using a California issue to try to score points for their church with mainstream US Christianity. There is a feeling in California that the LDS church made BYU's bed.
Baylor has been frankly religiously odd. They probably reminded the PAC of BYU. (This article, and the thoughful responses to it, are an excellent discussion on why the PAC is probably out on Baylor long term.)
TCU is a little bit of a different creature. Founded by Addison and Randall Clark with "a vision for an institution of higher education that would be Christian in character, but non-sectarian in spirit and intellectually open-minded", TCU is not your average religious school with a Christian word in it's name.
That goal sounds like the kind of religious school that PAC presidents can tolerate. Football is important at TCU. They have fought hard to get back to the big boy's table. If staying there means TCU has to further codify their methods to reflect their founders desire for intellectual open-mindedness (to fit PAC-12 standards), I am thinking that won't be a problem.
Adding TCU would immediately silence all the "PAC is against Christians" talk, so it actually would offer some strong added benefits by effectively underscoring out why BYU and Baylor are not in the PAC. It isn't that they have religious affiliations, it is that their religious beliefs either regularly interfere (or could interfere) with intellectual pursuits.
So that gets the PAC to 18, lands UT, protects the vitality of UT's and OU's football programs, but that only accounts for 6 Big 12 teams. The PAC needs 8 Big 12 votes.
Now it gets really interesting. With two slots left and Baylor, Kansas State, Iowa State, and West Virginia left, which schools does the conference take?
I think it's a no-brainer when you figure in TV, academics, geography, and religious terms, but most fans will hate the answer.
You add Iowa State. Baylor and KState are in markets already owned. West Virginia is far away. Iowa State is AAU and has a state-wide following in Iowa. It may be a state of only 3 Million, but it is fairly wealthy and you wouldn't have that market otherwise. Plus it allows the PAC and Big Ten to have a shared border ---symbolically that is something likely to be appreciated and valued by the traditional Pac-10 leaders.
That is 7 votes. This is where the PAC can get tricky.
At this point Kansas State would be in the driver's seat for the last slot in the conference. The PAC would have little interest in adding Kansas State. I suspect given the quality of Kansas State football, UT would be totally OK with leaving them behind.
If the Pac could somehow come out with an open slot, they could end up with a dramatically stronger conference.
If KSU is added, Baylor would be out. With the conference out of business the Bears would be looking at no future UT generated conference revenue. As it seems the SEC is uninterested in Baylor, the Bears' athletic budget would drop by at least $20 M a year overnight.
It is a very poor position.
Offer them a deal. If Baylor votes to be the 8th vote to torpedo the conference, the PAC will cut them a very sweet deal. If they don't, KSU gets the slot and Baylor gets nothing.
What would such a deal look like? Home and home games against UT, OU, OSU, Tech, and Kansas in all revenue sports at fat rates for the next 20 years. Structure it so Baylor would essentially net say $20M per year from those games (all slushed in from the top of a newly renegotiated PAC TV deal) as an independent. That way Baylor is effectively on the same tier as BYU. That isn't a bad long position for Baylor at all. The PAC can then use it's influence to help keep Baylor and BYU in the D4 mix (along with other friends of the PAC --- ND, Army, and Navy).
This opens another full slot for the PAC-12. Several schools make sense.
Options for the last all sports slot
AAU Missouri would be a strong add as they share history with the SW division, reinforce the idea of the PAC and Big Ten bordering each other, and offer good sports and markets. Missouri football is somewhat reliant on Texas recruiting and Missouri didn't really want to be in the SEC in the first place. Missouri football is currently having a good season. While not the Big Ten, this would be a much more natural home than the SEC.
And the money would be better.
Another option would be Notre Dame. I do not think the Irish would accept a full membership without requiring opponents that would create ridiculous divisions for most of the other schools.
Arkansas would be another option. They really like being in the SEC, but they aren't SEC lifers. This would be an elite academically affiliation with a lot of nearby rivals (unlike the SEC) and plenty of recruiting opportunities in Texas. Arkansas turned Texas recruiting into becoming nationally relevant in football and basketball in the last days of the Southwest Conference. They really haven't matched that in the SEC.
Today, Arkansas isn't thinking about leaving the SEC because the SEC has the better hand. In this scenario, the SEC would not.
(Arkansas used to be UT's #2 rival behind OU. For UT fans, A&M was always #3.)
The University of New Mexico would make a lot of sense too. They were a finalist when the Big 12 was formed. (An alternative plan would have formed a Big 14 with BYU and UNM joining.) They bring an unserved state (even though it is a small population state with little money.) and would serve as a bridge between the eastern PAC-12 schools and Texas Tech.
The addition of UNM could open the door to selling PAC brand in Mexico. (The PAC isn't currently looking at Mexico, but conceptually that is not far off of what I have read of the PAC's plans to develop more revenue streams by selling more merchandise to markets outside of their footprint.)
UNM has been hamstrung in football historically due to the fact that they compete with UTEP and New Mexico State for the limited football talent generated in the low population state of New Mexico. If they were the only school of that trio in a D4 conference, UNM would get the pick of that talent. Playing in this conference with PAC TV money would allow them to easily supplement their New Mexico recruiting with Texas recruits.
It becomes rather easy to see their football becoming competitive. They are an historic basketball power with one of the best winning percentages in the nation and a large, basketball crazy fanbase. The Pitt is one of the great college basketball venues in the US. Give UNM another quality 7 footer from Texas every 2 years and they would be an annual national title threat.
Their academics lag behind most PAC schools, but they do a significant amount of research which the PAC schools appreciate.
Colorado State makes some sense too. They are a pretty good academic school with a great, new, on-campus stadium. They do a lot of research and are currently very competitive in basketball too.
Colorado sees a large portion of their alumnibase move westward into PAC territories. CSU alumni are much more likely to settle in the Denver DMA. CU and CSU in the same conference makes more TV sense than KU and KSU.
If those 5 are out, Rice or Houston would make sense.
AAU Rice would be a great get from the perspective of the California schools. That would give the PAC the two best academic schools in Texas. Rice has a strong baseball program which matters to the California schools. Playing UT, OU, Tech, and OSU would make Rice's football attendance look quite respectable overnight. (Rice's small enrollment has become a huge problem in making their football relevant. One would hope the PAC schools would lay down the law with Rice about increasing enrollment as the cost to get in, but you never know...)
Another option would be to add Houston. Houston draws solid crowds on their own and would likely do much better in this PAC. Houston is a large university actively working to increase their research volume. It would read very well in the state and would serve as a strong platform for PAC recruiting in Houston --- currently lost territory for most of the Big 12 since A&M's departure.
I would think Missouri, UNM, or Arkansas would generate the most value. Lets say Missouri takes the spot.
Finally the PAC could consider adding Rice as an Olympic member. That would create 3 divisions in basketball and the other Olympic sports with UT, Rice, Tech, OU, OSU, Kansas, and either ISU or mystery team (Missouri, Arkansas, UNM, etc.) in a division, ISU (or mystery school), Colorado, Utah, ASU, Arizona, USC, and UCLA in a division and Cal, Stanford, OSU, Oregon, Washington, and WASSU in a division. That would allow the 20 football programs needed for fat TV revenue while potentially cutting travel costs dramatically at all the PAC schools.