Will read in a bit, but I was listening to Dan Patrick yesterday, and he talked about this and also did so with Tony Dungy, who played in the league back in the 70's.
There are safer helmets now that are available but not all the players wear them. Tony said they have a battle to get the players to wear mouth pieces and all of their pads. DP said that once they figure out a way to accurately test for HGH (he has been told off the record by players that they believe 60% of them are using it) and that is removed from the game, players won't be able to get so big and big at high speeds.
Lastly, nobody is forced to play football..not at any level. I could see the impact on the game through parents not allowing their kids to play the game and there being fewer people available and perhaps the quality could drop, so we could be in the window of the apex of the game as far as its quality.