They (and CSU) could be so much more as football and athletics programs. New Mexico may be a poor, sparsely populated state but it comps favorably with West Virginia (an even poorer and less populated state).
New Mexico borders a number of decently sized and decently wealthy states in Colorado, Arizona, and Texas with good football playing populations. They shouldn't have that much trouble pulling people in to play football successfully at their current level. They don't have to win national titles, but they should be able to be competitive in the MWC.
If they had Boise States level of success and support people would be bringing them up for Big 12 admission in each round of discussions. Even back in the 90s they were a darkhorse for a "Big 14".
They should be one of the flagships of the MWC.