Makes sense at this time.
NMSU's preference is to remain FBS, and it is QUITE POSSIBLE a slot may open up in an FBS conference following Big XII expansion and the trickle-down realignment.
NMSU has 2 more years as a sun Belt football affiliate (FBS), so there is no urgency for them to downgrade to FCS at this time (and a downgrade to FCS is what the Big Sky would be offering, if and when they ever do invite NMSU).
The trickle down realignment may not work out in NSMU's favor. It would depend on what C-USA would do in the long run.(if they stay at 12 if they lose 2 teams) I'm thinking that the only chance NSMU has of making it into another FBS conference is if the Big 12 decides to go to 14 instead of 12.(or if the Pac 12 for some reason adds 2 teams to move to 14)
There has been no movement on the Pac 12 moving to 14.(lack of good candidates) or the Big 12 going to 14.(seem to be interested in adding 2) While i personally think that the P 5 conferences will expand to 14 eventually.(and stay there) I don't see such a expansion from either the Pac 12 or Big 12 at this time. I would think the Big 12 will expand in a few years if they go for the UCF and USF combo this go around. While week they offer 2 good markets and a recruiting area.(i would think people will go see some of the bigger Big 12 play in Tampa) I think the Pac 12 only has one guaranteed school it will expand with is Boise State.(i don't see a good 14th school)