I have talked a lot with Jack Graham on this point and he says that the school needs to get its stadium built and get to another few bowl games. If they do, they will be ready to compete. CSU is becoming the largest school in the state and has very solid ties with Big 12 as they are mostly land grant institutions. The politics favor CSU even more than BYU, but CSU is rebuilding its athletic programs -- and doing a good job at it. They are only a few years away at this schedule.
If BYU gets an invite, it may actually be delayed to simply block the Pac 12 going forward and help BYU keep its contracts, but also to allow CSU to prove itself in the interim.