You didn't leave any teams off the list. I give you props for that. However, if New Mexico State is better than the rest you mentioned above (which I might like the idea of the Aggies to re-join the Sun Belt as full members instead of fb-affiliate mode), that leaves either UTA or UALR to have football a.s.a.p. Look at C-USA for next season, they will have 13 members to start off (including Old Dominion after its 1st year as an FBS Indy), leaving Charlotte alone as the only non-football member until their football program to join in 2015. I bet that C-USA would secretly plan to gran another Sun Belt member to have 14.
I believe that conferences are willing to wait a few seasons for their schools to get their programs up and running. I don't feel that they will force decisions to fill short term spots with long term affiliations.
There are plenty of 'Olympic only' schools available to the SunBelt, in all parts of the country, so they could add them anytime. The priority is to lock down a few 'up and comers'. They already jumped on App State, G.State, and G.Southern...which is pretty solid.
-Jaxsonville State would be alright....though, I'm not certain that Alabama can support another team?
-Also, in the next few years...New Orleans U. will have a team up and running.
-UMass is a great school, but, they are so far away and in the opposite direction of the two other far away schools. I just don't see the travel working out, unless everyone agrees to it.
And don't forget....the next ripple in conference realignment means ULL and Ark State are probably gone. Then Texas State and Georgia State would be the next most attractive.
I'm starting to feel like the SunBelt needs more than just one or two additions. Get them in now...so if ya' loose more....you don't have to add again.