The problem with the football helmet is that it really isn't designed at all to protect against the acceleration/deceleration head injury that is the concussion.It is designed to protect the head against blunt force traumas, and it does that very well. The skull fractures that were the problem of football in its earliest collegiate days are almost a non-issue today. Where we hit boundaries in the concussion conversation is when we continue to think of the helmet as a means of concussion prevention when it is nothing of the sort.
Football's concussion problem stems from the fact that the head sits on what is essentially a whip. The neck has a wide range of forward and side to side motion, and in many concussions, that motion gets the head moving at a much higher rate of speed in a big collision than the body. That, in turn, worsens the damage suffered by the brain when it moves during the collision and impacts the skull. So what if the first step toward reducing concussions isn't making the helmet stronger, but instead reducing the neck's ability to literally whip the brain into the skull?
Focusing on the neck instead of the head changes everything. You might look at a firm brace that connects between the shoulder pads and the helment, or even a halo like device, either of which preserves lateral head movement while stopping the whipping action of the head. Perhaps it would even be worth examining retired players who used to use the now obsolete neck roll pad of the 1980s. I don't have the exact solution, I'm just saying that I think we're trying to create the wrong solutions right now.
Of course, any solution that reduces forward/backward/sideways acceleration to keep it in line of with that of the body is going to have some critics. Criticisms that a neck device would change the game should be roundly criticized. The game is always changing, and it needs to change in some way to prevent concussions. And this solution would not end concussions, it reduce them. But other criticisms should be examined. Would stiffening the neck possibly increase the risk of spine injuries? Would the reduced forward/backward/side-to-side motion create a significant increase in other very serious injuries? Those are the types of criticisms that should be examined, but which I can't answer at this point because this at the brainstorm level for me.