As much as I hate to say it - the Montana schools won't be attractive for a media contract even if they have the best ratings in a conference. Those TV execs are too in-love with market size and the conference heads don't want to share the purse with schools that'll likely beat them. If you're a cupcake in a major media market, you're pretty well set with all of this realignment. Still...that entire state shuts down when the Griz or Cats play and they'd walk right in and be smack dab in the middle of the FBS in attendance today. Colorado State only averaged 240 more fans than Montana last year. Montana outdrew programs like San Diego State, Utah State, Tulane, Vanderbilt, Duke, UNLV, Wyoming, Nevada, New Mexico, New Mexico State, Rice, Texas State, etc., etc..
There are reasons that Montana would make sense for this new Pac-whatever, especially if Utah State is the tier of program now in it, but I just can't imagine them going directly to FCS programs to fill the conference out. I think the belief is that any lower-level FBS school is better than any FCS program just by virtue of being more known. That adding FCS programs to meet minimums would be pure desperation, rather than fairly logical. I have more hope that the Mountain West would do so out of sheer necessity than desire, but they've never directly added a program in transition before and would have to convince existing members to accept programs that'll likely jump them rather quickly. I think they'd rather skim Texas for fourth-tier programs just to have a Texan presence than go for the best programs left within the conference footprint.
Montana has had at least one invitation to the MWC before, but it is absolutely a package deal with Montana State and that was an issue 10-15 years ago. I mean there's no good reason for North Dakota State to still be an FCS program after winning damn near everything for a decade other than NDSU likely dominating a lesser conference without meaningfully expanding that conference's TV footprint and no P4 conference is going to add a FCS team outright. All that success has basically just made it more difficult for NDSU to fill out their non-conference schedule. Hell, Montana's last game against an FBS foe was a win @ Washington a few years ago. These are programs that have long outgrown the FCS, but are seemingly unwanted by any conference in the FBS.