The only counter to SEC is for the other conferences to isolate the SEC. Unfortunately, the SEC's easy counter to the 'alliance' is to peel one of the conferences off. If any of the three paired with the SEC it would instantly be an utterly dominant force.
I'd be very disappointed, although not surprised, if the ACC commissioners aren't also talking to the SEC and ESPN about options. An SEC-ACC 'alliance' makes a lot of sense for geography, rivalries and power. Unfortunately, a B1G-SEC alliance would be the most valuable. So lucrative, in fact, they could absorb/reimburse the buyouts of teams like Clemson and FSU to bring them in.
A writer, and I can't remember who, recently said that this re-alignment is going to have two kinds of players: The administrators/schools/conferences who think there's rules about this sort of thing. And the ones who will come out on top.