Remove the hard plastic from the shoulder pads and helmets, thus eliminating the metal reinforced face guards,
At the beginning of the 20th century there was a move to ban college football. Football changed the rules like outlawing the flying wedge etc. and survived. Football might have to look at big changes to survive.
In rugby its all about getting control of the ball. So your emphasize is tackling the ball more then a “big hit” on the player. When the knee hits ground you must release the ball, basically its a “controlled fumble”. If the ball is free then play continues, if the ball is contested then a ruck or maul forms. This is a “pushing contest” with very specific rules abut how one gains possession of the ball. I could go on,, but the dog is demanding to go out!