No one in the Sun Belt would join the MAC as a solo entrant. First the MAC isn't going to add a full member that is that much of an outlier and second none of the Sun Belt members would be willing to be that far out of the regional footprint. If the MAC were going to 16 and there was a division with half the members in the south? Maybe. There are some schools royally pissed in the Sun Belt right now over the votes our rep made at the last NCAA meeting but don't see anyone so mad they raise their overhead that much going alone to the MAC.

As for CUSA, I think the MAC's shot at WKU has passed and it would make hundred miles of hate a non-conference game even if it continues, don't see Marshall thinking third time's the charm unless they were really really really unhappy with CUSA. After that you are talking ODU as the next reasonable option and while the AD there was the AD when WKU made overtures to the MAC again don't see that as likely. That takes you down to MTSU and they have a pretty nice location in CUSA East.