As long as there are poor people with some athletic ability and fans willing to watch them, there will be grid iron football players.
Today it is confined to a niche professionally and is almost totally absent from most youth sport systems.
I know MMA fans might take exception but I think I'd lump them in with boxing fans of the past. Maybe there is some clear delimiter between MMA fans and boxing fan of the past; I can't think what it would be though.
Lots of the kids MMA events don't even allow head strikes and especially not the particularly dangerous elbow strikes while on the ground.
Boxing makes it hard to have that distinction. My prediction is that MMA will also go through this when people start realizing that the head trauma stuff is nearly as bad in MMA as boxing.