After watching this video and watching the antics of Cortland Finnegan, I believe that fighting in the NFL should be as legal as it is in the NHL. Of course like in hockey, there will be rules to make it safer and a minimal penalty, but nothing like the massive fines players expect to get now. This will also make it less likely the rest of the team will get involved. But I don't expect this to happen any time soon. There is also a racial aspect to the whole thing and I have to bring it up. The NHL is like 99% white and the NFL is like 70%+ black (guesstimates) and there's a subconscious mentality to punish black players more than white players. It's the same thing when it comes to the law, blacks get treated worse than whites.
But having "legal" fighting in the NFL would make it better, that and allowing coaches to challenge penalties and allowing more endzone celebrations.