You would quit donating and buying season tickets? I wouldn’t.ISU to the Big 1G is never happening. ISU can't add more than they'd take away from the pot.
The only realistic scenario for ISU is the Big 12 continues in its current form. OU and TX leaving would relinquish power 5 status. The TV contract would fall through the floor. The tickets and donations would fall through the floor. ISU would be absolutely devastated.