I think 10 is the number if Mizzou stays because it keeps everyones money the same. And we basically traded college station for Ft. Worth. If Mizzou leaves we will need 3 teams to come in to replace the market loss that Mizzou brings to the B12.
Also it has been indicated (don't remember where) that Texas likes a 10 team league and since they are giving up, unequal revenue sharing, rights and hs content on LHN. There there could be some kind of payoff with 10 team league. However, like I indicated above it Mizzou leaves we will need multiple markets to make up for the loss of what Mizzou brings to the conference.
I know Beebe is no longer with the conference but remember he was in conversations with the BE. It could be that there is a handshake deal that the B12 wouldn't take anyone but TCU, provided Mizzou stays. Not sure the B12 wants to be considered the reason the BE failed. Even though it wouldn't really be the B12's fault.