I do think the SEC could have its conference channel with only 10 members. The Big Ten probably could get away with having only 10-12 members. However, the ACC may not be in a position to go that route. It is possible the 2 factors are connected. Likewise, it is possible they aren't connected because conference network are a byproduct of the natural evolution of televised collegiate sports in the US.

When I search my Roku 2 for channels to add, I come across these options in addition to the already established networks: WAC Digital Network, Rocky Mountain Athletic Conference Network, PA State Athletic Conference Network, Big XII Network, Great Northwest Athletic Conference TV, NE10 Now, Conference Carolinas Digital Network, Northeast Conference Network, NAIA Network, Northern Sun Intercollegiate Conference Network, South Atlantic Conference Network, Lone Star Conference Digital Network, Centennial Conference Network, CIAA Sports Network, Mountain East Conference Network, Great Midwest Athletic Conference Network, NESCAC Network, KCAC Network, Conference USA TV, CAA TV, Appalachian Athletic Conference Network, Midwest Conference Network, MIAC Network, the ECC Network, Ivy League Network, Ohio Valley Conference Network, Atlantic Sun Network, and there are still more (I got tired of typing them all). Some are just as elaborate as the ACCN. While others may be more like the ACCN Extra.