The Big Ten and Pac-12 conferences announced a new extended schedule agreement on Wednesday, that will make several changes to inter-league play for most of the sports. According to Pete Thamel on Twitter, the agreement's main attraction is the fact that each team will play an inter-league football game against the other conference starting in 2017. There is a chance that could happen sooner than that, but there's plenty of time to figure out how exactly the new agreement will work.
The schedule agreement also includes changes to the other various sports, and of particular note is the fact that things could be changing much sooner for the men's and women's basketball, as one of the more prominent sports. Meaning that we could see more play and cross-promotion well before 2017.
On top of that, the agreement focuses on things like cross-promotion between the conferences, most notably on their television networks. This has all been done to compete with the expansion of the other conferences. As opposed to expanding themselves, they've increased activities with others to strengthen one another and keep the attention directed at them.