You make some good points, but there's a couple spots I mildly disagree.

To point 1) UNLV is listed as a tier 1 Research institute. All but 3 P5 schools currently have that designation so it's a must for the PAC12. That provides one option for PAC12 expansion. Other Tier 1 schools are Colorado State, New Mexico, Hawaii so not great.... UNLV has serious potential though with the size, location, facilities, especially if the PAC moves headquarters to Vegas.

2) Kansas actually makes a fair addition to the Big 10. Toughest part is finding a 2nd fit though.

3-5) Complete agreement

6) Does BYU have a larger fanbase than these schools? They don't get more viewers. You can find solid excuses for that, but the end result is the end result. I think UCF and Cincy are the clear top two options. They've been better on the field, better recruiting, better TV ratings and are better geographic fits than BYU.

7) The next two are indeed tougher.

Houston has great geography, big market, and maybe not as big a deal to splinter Texas if the two big dogs are no longer in conference. They've also outperformed BYU on the field, but not in TV viewership.

BYU is solid in every regard. They're not as good on the field as UCF, Houston, Cincy (even in this great season, Cincy trumped them). They've drawn fewer viewers than UCF, Cincy and Memphis, but more than Houston or any of the Western options (Colo St, Boise, UNLV, SDSU). Similarly the geography is bad - average of 1300 miles to each school and nearly 2000 to W Virginia, but better than other far west options. BYU also has the most history/prestige (even if it's 35+ years ago now), but some other baggage.

Memphis is a perfect geographic fit, driving distance to a lot of other schools. They've outdrawn BYU in TV viewership and are very close to them on the field - 37.5% against P5 (BYU is 39.5%) and 55.6% overall (BYU is 60%). Academics are worse, but that's never been an emphasis point for the Big 12 and Memphis has its own checkered history.

I think 2 of these 3 get the invite. Depends how they weight Houston's Texas-ness, BYU's prestige, BYU's baggage, BYU's geography and Memphis's general okayness.

Other westward schools pose similar issues as BYU with less reward.

9) adding 6 G5s could work and then could add more Western teams in that case with BYU. At the point though, you're taking 8 P5 teams (possibly one or two less) so it's basically half G5.