The SEC is actually running out of options to get to 16 with the ACC schools off the table. West Virginia and Missouri are solid adds, but that leaves a choice between Kansas, Kansas State, Texas Tech, TCU, Baylor, and Louisville for team #16. Tech doesn't look that horrible in that picture.
Big Ten also is getting boxed out by the ACC expansion, leaving only Rutgers in the east as a viable option, otherwise they would have to look into some combination of Missouri, Kansas, Oklahoma, Texas, and Iowa State.
Notre Dame has said they would prefer ACC over Big Ten if they joined a conference, and the ACC saying they want Texas by themselves spells this out. Their #1 aim for team 15 & 16 is Texas-Notre Dame. If Texas says no then they will see if adding Rutgers will land them Notre Dame. If the Irish still refuse then they can add two of Rutgers, UConn, or Louisville and still be OK.
The Pac would love to "demand" Texas-Oklahoma-Kansas-Missouri but those schools all have options and the politicians will go to bat for little brother in each of those states that have one.
If the Pac is willing to take Tech and Okie Lite, it can land both Texas-Oklahoma. If not, then there is no superconference for the Pac. Not saying that is a bad thing, but I do believe that there is a private push to put the 4 superconference idea into motion and eliminate the current BCS format. Who knows if that will be allowed to work with 1 or 2 16-team superconferences and 1 or 2 12-team conferences with two "low-end" near-BCS type conference amalgams still in existence.