If SDSU and UNLV joined the WCC, they could go Indy for football and BYU, UNLV, and SDSU could play each other every year. It is possible, if they have guaranteed scheduling for football.
Add Hawaii to that arrangement as well (they are in the Big West, and would love to be Indy in football if they could).
Adding a few public schools to the WCC would probably destroy the MWC.
Or they could join the AAC for football (SDSU almost did this already).