So with the CUSA smarty schools, Rice and Tulane, getting routinely killed in D1-A FBS football, is their any chance they would decide to join the Southland if somehow CUSA gets ripped apart by the Big East (UCF/UH/ECSU) MWC (SMU/UTEP) and possibly MAC (Memphis/Marshall) and SBC (UAB/Tulsa/SoMiss) (I know its a longshot but theoretically) where they could better compete with the FCS schools and still be in a D1 conference? Could it just be a football only membership? Just shooting off some ideas feel free to shoot them down but from a Texas guy this doesn't sound that crazy but obviously if they could stay in CUSA (even with 5+ new members) and still get the good midmajor TV money they probably wouldn't leave but if they could win games, cut travel and save scholarships it may be more feasible and possible though not probable.
I would think they'd choose a 12 team WAC before they moved down, especially since the East division would be very localized.
I like your thinking, but if C-USA is going to have that many members taken, it will be over a long period of time and they will just reload between movements. I doubt they would lose more than 3 members at one time making reloading a much simpler task with Sun Belt schools or the likes of Charlotte. Then down the road if they ever lost a couple more to say the Big East, the next replacement schools could be picked by who has been successful.
Now, if there are a lot of schools moving and C-USA reloads with more teams out East and doesn't add teams like N. Texas, they may consider moving to the Southland/WAC but I doubt that would happen. I would be stunned if N. Texas wasn't brought in after SMU left.