Looking at our roster/recruiting targets, I can't help but think that the coaching staff could/should be looking to move to the 3-4 down the road. We have a ton of hybrid types who could fit perfectly into that scheme...
3-4 Rush LBs: Spence(deadly off the edge), Lewis and Marcus (guys who aren't good in coverage but are amazing pass rushers)
3-4 DEs: Washington, Bosa, Pittman, Bennett, Sprinkle (DT frame with skills to play the 4-3 DE but better at the point of attack, and lacking elite speed)
Nose Tackles: Schutt, Hill, Price, Munger(?), Marcelys Jones, Chris Carter
The 2014 linebacker targets could also fit in very nicely. I've heard that both Booker and Berger project as Viper types, which would definitely translate to the 3-4 OLB spot. Also, with both Mitchell and Johnson committing, we have some great incoming talent at MLB, but are still recruiting guys like McMillan and Garrett who are ILB types as well. And Mitchell could honestly play any of the LB spots in a 3-4, he's great off the edge and can also play the middle. And with how great ND and Bama have looked recently, I bet Urban has taken notice.