CSUF, CSUN, UCI aren't going or will be invited to the Mountain West.
the only low probability invitees are Hawaii to resume all sports (at considerable cost, which is why they are in the Big West) or UC Davis which would ahve to invest $200 mil plus in football to move up the chain to what is a 2nd tier conference at that
the Big West has an identity that is pretty much secure other from getting tougher to compete in Basketball and Olypmic sports due to the changes
it is possible WSU & Ore State could get Mountain West invites, and who knows what becomes of Wash, Ore, Stan, Cal
I'm sure the Big west would welcom Stan/Cal with open arms for Olympic sports, but seriously doubt it would come to that for them, but you never know.
the Big West is the 2nd best in academics of the sports conference after the Pac-12 interestingly, and may be #1 after the Pac-12 disintegrates....interesting