I don't see the existing P5 ever admitting another new member to the club to share their legislative autonomy. However, if the Big 12 were to vanish, I could see a path for the AAC to "reclaim" it's original status that it's predecessor the Big East held, which I never did before reading this article. Aresco and company are goooood considering the hand they've been dealt. They would basically replace the Big 12 rather than be a new member, and besides, they were already kind of a member once before anyway.
It's almost too bad the alleged collusion was leaked to Bowlsby as it would have been fun seeing the AAC break the glass ceiling in spectacular fashion.