The SEC knows it would never get UNC. UNC would never leave the ACC because the ACC does what UNC wants. UNC runs the ACC.
Its a small fanbase relative to another team within the state.
I think if the SEC could get a team in North Carolina, they would want UNC. Ain't gonna happen, but it sure would be funny to hear the howls coming out of Clemson and FSU if it did.
NC State would leave though. It would give the SEC millions more television sets. It doesn't matter if most people in the state would or wouldn't watch. Distribution is all that matters.
If they can get into NC, the SEC can then launch their proposed SEC network in NC. Since cable providers pay to carry a channel, the SEC makes money regardless of if people are watching NC State play or not.