The thing about either the Big Ten or the SEC breaking away is that either one, and particularly the Big Ten, will find out very quickly that they aren't nearly as appealing when they are not competing in a national context. They're going to get premium media rights rates when the importance of Rutgers or Northwestern or Purdue is suddenly magnified 50 times bigger than it was? The Big Ten won't be able to hide the slop that makes up two-thirds of its football conference. The SEC is deeper and would have more appeal, but only by degrees.
Part of the appeal of these leagues is that they -- well, really the SEC -- dominate in a national context, and the very top of the Big Ten does too in the past three years. But when they are eating themselves and only themselves week in and week out, it isn't nearly as compelling.
Given that there are no real rules or laws anymore, I don't see the antitrust threat as being what it once was, which is why I'm still quite sure you'll see the superleague formula come about eventually: A generous helping of SEC and Big Ten programs with broad brand appeal, filled out with selected other premium brands chosen from the ACC and Big XII -- your Florida States, Clemsons, North Carolinas, and such. There really are no slam dunks from the withered Big XII to be honest; maybe Texas Tech and/or Arizona or BYU? The ACC really does offer more brand value, but you're only talking about cherry-picking the best ones, anyway -- enough to get to 28 or 32 or so.