I am as far from a scientist as you get... and i struggled to pass earth science im middle school so there is that....
In the end i think they can improve helmets only so much football is violent and energy on impact is going to go someplace and hits to the head are always gonna cause some impact so there is no real magic cure.
I think the other piece as I understand it is that it's not always the direct contact it's the brain knocking on the inside of the skull with abrupt stopping and honestly I am not sure how you stop that with a helmet... I am sure of this they are probably trying everything they can to improve safety but really big men moving really fast and colliding is gonna cause problems always