NCAA bylaws state in order for a conference to host a CCG with 2 divisions, the divisions must play a round robin schedule. There is no way a 13 member conference can play an 8 or 9 conference games and a round robin division schedule with uneven divisions (see the MAC).

The MAC was in violation of this bylaw when it had 13 members. The reason the MAC was allowed to get away with it was because the MAC is small potatoes. A power conference will not be allowed to get away with it. So unless the ACC is going to play 12 conference games (round robin), then the ACC will either need to kick out 1 more member to drop down to 12 football schools or add a replacement school to get back to 14 football schools.