I think the next 2-3 years will be huge for the NAIA. I was shown a "prospect list" from the NAIA by one of my contacts. Notes on the list said it included those in active discussions with the NAIA for membership and also asked for introduction assistance. So the list runs the gamut from those the NAIA thinks would benefit but no contact yet, to those who are planning on applying next year. I can't comment on which schools were on that list, but I will give you some basic idea:

It's over 100 schools long
The biggest group are NCAA D2 schools
There are about half as many NCAA D3 schools as D2 schools.
There are about half as many NCCAA schools as D3 schools.
There are about the same number of USCAA schools as NCCAA schools
There are a handful of "start ups" without current athletics.

Of course, there's no guarantee ANY of them will become members; it does show you what the NAIA is thinking, what their goals are and what they're doing about it.