I believe this would be a huge error. Every playere would have to learn a new roll and some would fit and some will not. This would require retooling and putting an NFL quality and playoff caliber defense on the field before next year starts. Big risk.
There's much more to employing the 3-4 than just having four decent LB's and rolling with it.
As mentioned above the goal here is to put a playoff and SB quality defense on the field. IMO a team reloads when they are prepared to essentially start from scratch and build from the ground up.
I do not believe the Packers are in that place at this point and would rather see them fix the pass rush problem which would go a long ways to improving the numbers on defense and by no means requires an overhaul of the defense.
If teams could just switch to the 3-4 and go to the SB the following year I would imagine everybody would be doing it. Besides there's no big difference in numbers between teams that are good at the 3-4 and the ones good in a 4-3.
The key is being good at whatever it is you go with and I would be anxious to see how much better this "D" would be with a solid pass rush than I would to see them change the whole defense around.
"The train is leaving the station."