MWC, MAC, Sun Belt, and CUSA. That being said, they only have 5 teams in their conference that were bowl-eligible last year AND two years ago as well. Odds are there will be at least 1 and possibly 2 open spots there. I'm guessing the most likely games to be vacated there would be the Bahamas Bowl and the Armed Forces Bowl.
Other strong possibilities include the Heart of Dallas Bowl or Buffalo Wild Wings Bowl (if Big 12 doesn't have enough teams), Christmas Bowl or New Mexico Bowl (both if Pac-12 doesn't have enough teams), or 1 of a variety of bowls contracted by the SEC (including Liberty Bowl, Belk Bowl, and Texas Bowl).
As I mentioned before, I think the Christmas Bowl is probably the most like scenario, but I could realistically see us in several of those spots mentioned above - especially the Heart of Dallas Bowl, New Mexico Bowl, Armed Forces Bowl, and Texas Bowl (I also think BWW Bowl would pick us, but they're a little less likely than the others to have an opening).