The WAC is not unstable because it has only ten teams. The WAC has stability problems due to geography, i.e. it is really two conferences. The west consists of FSU, BSU, UN, UH, and SJSU and the east being Rice, LTU, SMU, Tulsa and UTEP (although UTEP could slide either way). This creates divisiveness in voting and interests. It also makes the WAC ripe for predation by other conferences (MWC, CUSA).
If the WAC were to go to 12 teams you have hit upon the most likely candidates but all of them have their drawbacks.
But wouldn't having divisions get rid of this problem?
Still, if what you say is true, the conference may not last long anyway, and all of the MWC/CUSA/Sunbelt pundits will have been correct on the WAC's future. (Double serving of crow, please ;D :'( )
Montana would be a good candidate since they already make all of the D1A criteria and would be competetive now. There seems to be very little impetus there for moving up to D1A and they may be politically tied to MSU.
I don't think the Griz are politically tied w/ MSU. Could be wrong, but I don't think so. You are correct though that there seems to be very little impetus for going IA. Let's just say they're going through the GSU (Georgia Southern) syndrome (i.e. they want to be the big fish in a little pond). However, there used to be some impetus for going IA on the MSU campus. I don't know what happened with that.
PSU, also of the BSC, has decent facilities and a great market. They have yet to show they can consisitently capture a significant proportion of that market, however.
The Vikes are on working on that, but the problem is that my Ducks as well as the Beavers have lion's share of the Portland market. There has been some talk of merging PSU w/ the Oregon Institute of Technology near Klamath Falls. The merged campus would be in Portland. For more info, I'd like to recommend www.oregonlive.com,
the Portland Vikings forum.
If SJSU does not make it in D1A (and their chances are as good or better than half of the SBC and a good chunk of the MAC) then one of the above western schools will be pursued if the MWC takes two or less teams from the WAC. If CUSA takes a team and the MWC stand pat or takes only one team, look for the WAC to invite an eastern and a western team from the above list. The sad part is, those teams might just say no thanks.
Here's a horror story for Spartan fans. Let's say that SJSU survives the IA cuts, but the WAC still splits up. With a majority of the WWAC teams headed for the MWC and eWAC teams headed for the Sunbelt or a SW conference, where's SJSU going to go???