Once defences learn how to stop the pass there will be a shift back to running the ball more. Who knows when that will happen.
By the way, here is a great website where you can submit questions and get an answer from Vic Ketchman, who currently works for the Green Bay Packers (just so you know, he doesn't respond to every question, but he does read each one). He's been covering pro football for about 40 years. He has also worked for the Steelers and the Jaguars, so he's got a following from a wide area. http://www.packers.com/news-and-events/ask-vic.html