According to this source the Vikings might be thinking dropping Pagac as defensive coordinator and switching to a 3-4 defense. The biggest problem with this would probably be Allen making the switch to OLB. I don't think that's going to happen.
In that case we can probably trade him to team that is trying to make a playoff push and is willing to cough up a first and second rounder for him. The player that would benefit most from the switch would be Everson Griffen. He would thrive in a 3-4 as the LOLB.