Well, see that's the problem. That's more wishful thinking than reality. Really, you want the ACC to be in a weaker position, so you're throwing these scenarios against the wall, hoping something sticks.
Your own example proves the point. For you to get Florida St into the Big 12, you had to have a nightmare scenario where you have a bunch of teams leaving the ACC, and Florida St is just looking for a lifeboat. Well, that's not an endorsement of the Big 12. That's just them being at the mercy of fate. You don't have a scenario where the Big 12 could pull in a team like Florida St by their own accord.
That's my whole point. The Big 12 can't offer anything to entice good teams to come, because they can't offer more money. Aside from that, this idea about NC State to the SEC or North Carolina to the Big Ten don't really have any basis in reality. There hasn't been anything to indicate these schools are interested in moving. Message board rumors don't cut it. Besides, you are leaving out one big problem. For the ACC schools to leave, that means the GOR has to be overturned. If that's the case, it means the GORs for all the other conferences can be overturned. The Big 12 would have its own vulnerabilities if this was the case.