We're given 3 options - each of which is unlikely.
The least unlikely is that WSU moves on to another league.
Elgin will NEVER expand the Valley. He's been opposed to that forever. If the MVC would expand, the pattern is that schools from Illinois would be added. Anybody ready for Eastern Illinois and Western Illinois - or maybe SIU-E and Nebraska-Omaha?
Moving to FBS FB is economic suicide unless you get a TV contract immediately. UNI has the program with the best likelihood of any level of success in FBS, but UNI seems to have fairly intelligent people at the top (AD and Pres). If CaseyGarrison can be believed at any level, MSU doesn't share that, but MSU is so broke and their FB program is so bad, that their going FBS is nearly laughable. Not really - it's actually very laughable.
That leaves WSU jumping conferences as the least unlikely of the unlikely options. The Power 5 going to the NCAA for some autonomy, stipends for athletes, etc. could change the scenario. If athletic stipends are allowed by the NCAA, WSU will be all over that like white on rice.
WSU's current success - followed by a major commitment to spend the dollars to pursue excellence - could change the scenario for WSU getting an invite from another conference. If the Power 5 throw down the financial gauntlet, the more elite leagues outside the Power 5 may want to take immediate steps to bolster their competitive position. Gonzaga, WSU, VCU, and a few others may become attractive targets.
Within the last decade, the MVC was one of the elite conferences outside the Power 5. Now, with the exception of WSU, the MVC has become the Horizon League.