Very sad indeed.
The thing that annoys me about this whole concussion debate and generally making the game more and more like flag football in the name of safety is that there are people all over the country who do far more dangerous jobs for far less money. If a player is worried about his safety then pick a different career. Lately the NFL has been going overboard with safety and it has hurt the entertainment value of the game and even though there is no evidence to suggest that concussions had anything to do with this incident the media is already spinning it.
That being said it is very sad anytime anyone life is taken. He was one of the best to play the game, may he rest in peace.