Apparently the announcement of the ACC Network caused them to panic about their position in the college football universe. Not sure why they weren't panicked before.
I'm also not sure this isn't simply rearranging the chairs on the deck of the Titanic. The league exists at the behest of Texas. Perhaps, maybe, Texas is throwing the rest of the league a bone here. They will make more money off of this. Their tv contracts guarantee an equal revenue growth for each team they add. Meaning if they are making 30 million per team right now, then each new school makes the revenue go up 30 mill a piece. The key here is, that any new addition will have to agree to not getting a full share right away. TCU and West Virginia are just now getting full shares this year. So, for a few years, the 10 schools that presently comprise the Big 12 will get a bounce in revenue until the new schools become fully vested.
Some folks have said that ESPN and Fox aren't going to be happy to be shelling out more money for what is surely to be lackluster additions (BYU, Cincinnati, Houston, UConn?) Well they agreed to the contracts! They did this in order to keep the Big 12 together. ESPN/Fox believed it was actually going to be cheaper if the Big 12 remained a conference, instead of several teams going west to form a PAC 16 and then the conference imploding. So, they wrote it into the contract that they would increase shares per teams evenly if the Big 12 expanded. Now, pay up.