I have to think the G5 would look a lot different had the Big 12 fought for and received permission to host a title game with just 10 members:
AAC North: UConn, Temple, Navy*, Cincy, Memphis
AAC South: ECU, UCF, USF, SMU, Houston
C-USA East: Marshall, MTSU, UAB, USM, FIU
C-USA West: Tulane, Tulsa, UNT, Rice, UTEP
MWC MTN: UNM, AFA, Colo St, Wyoming, Boise St
MWC WEST: UNLV, Nevada, Fresno St, SDSU, Hawaii*
SBC East: WKU, FAU, GA St, Troy, USA
SBC West: ULL, ULM, Ark St, LA Tech, UTSA (non FB UALR)
WAC: Idaho, San Jose St, Utah St, NMSU, Texas St
(Non FB Denver, Seattle, UTA)
You might maintain that had ECU accepted a FB only invite to the BE that the schism might have never occurred.
The WAC would need to choose between finding long term western replacements or accepting FB only members looking to move up from the Southeast like ODU, App St, GA Southern, Charlotte, Coastal Carolina, Liberty, and JMU.
Well the fact that you don't even need 10 members to hold a CCG, the Big 12 could have stayed at 9 since you either need to split in even divisions or play a round-robin to have a CCG.
That means that the AAC would probably still be the Big East with West Virginia, USF, Cincy, UConn. Then with Memphis, UH, Temple, and TCU since the C7+ND could still be part of the conference.
Then the PAC-10 wouldn't have to expand so the MW will still have Utah and BYU.
MW still have: SDSU, UNLV, CSU, Wyo, Utah, Air Force, BYU, NM. With BSU added most likely. (9 members)
The WAC would then have ID, NMSU, Hawaii, SJSU, Utah St, Nevada, Fresno St, LA Tech. (8 members)
CUSA would still have UTEP, SMU, Tulane, S. Miss, Tulsa, Marshall, UAB, ECU, UCF, Rice (10 Members)
Sunbelt would still have UNT, ULM, ULL, FAU, FIU, WKU, MTSU, Ark St, Troy (9 members). S. Alabama?
UTSA, Texas St, ODU, Charlotte, Ga st, Ga So, App St. would most likely not have been invited to FBS. Possibly Tx St & UTSA for the WAC or the Montanas would since it would be a stable league.
Still the Big 10, ACC and SEC would have expanded because they didn't have to expand to have a CCG.
AAC East: UConn, Temple, Cincy, USF, UCF
AAC West: ECU, SMU, Houston, Memphis, Navy*
C-USA East: Marshall, MTSU, UAB, USM, FIU
C-USA West: Tulane, Tulsa, UNT, Rice, UTEP
MWC MTN: UNM, AFA, Colo St, Wyoming, Boise St
MWC WEST: UNLV, Nevada, Fresno St, SDSU, Hawaii*
SBC East: WKU, FAU, GA St, Troy, USA
SBC West: ULL, ULM, Ark St, Texas St, UTSA
SBC non FB: UALR, UTRGV
WAC: Idaho, San Jose St, Utah St, NMSU, LA Tech, NDSU, Missouri St, Northern Iowa
WAC non FB: Seattle, Denver, UTA, Wichita St, North Dakota, South Dakota, South Dakota State, Oral Roberts
The MVC winds up with Milwaukee, Omaha, and UMKC. The Horizon takes Fort Wayne and Western Illinois.
Utah Valley, Chicago State, and Bakersfield are left behind.
CUSA went to 14 when the CCG rule was 12. They lost a team and went back to 14.
There are factors other than the CCG rule.
You would still have to account for the issue of the Big Marinatto chasing after Boise State and San Diego State.
The Mountain West was down to 8 football teams when Boise and SDSU said they were leaving. It's very likely that, no matter what the CCG rules were, the MWC would have added San Jose State and Utah State anyway, and that they would have taken Boise and SDSU back after that.
Also, IIRC, the BE invited Tulane and East Carolina at the same time, and if the AAC had stayed as-is after Boise and SDSU didn't join and after Louisville joined the ACC, they would have had these 10 members: UCF, Cincinnati, UConn, East Carolina, Houston, Memphis, USF, SMU, Temple, Tulane. Navy and Tulsa are the two current football members that would have been out if the AAC stayed at 10.
And as arkstfan pointed out, CUSA at the time was stuck on the goofy idea of getting larger to supposedly minimize "travel costs", so that conference wouldn't have stayed at 10 members, and the CUSA overexpansion coupled with the MWC adding USU and SJSU would have meant WAC football was doomed anyway.