I could see a scenario that played out with Sac State supporting the Cal Poly and Davis associate membership, expressing an interest in having a similar arrangement after the Big Sky increased its full membership. Which it did with the additions of UND and SUU. Without Sac State, the Big Sky would still have 10 full members. And now, the Big West with this announcement. It doesn't make sense that the Big Sky would add Poly and Davis for football while simultaneously oppose Sac State having the same arrangement.
As for the Big West, I could easily see them expand to 10 to 12 teams; Sac State, CSUB, and Hawaii. A number of conferences have 12 or higher; A-10/14, the Atlantic Sun/11, Big East/16, and Southland, Southern, Colonial, Sunbelt, Northeast with 12.