As an Australian, the only way I can see to make NFL safe is to remove all the padding and helmets. It’s a surefire way to get rid of the head to head contact and shoulder charges!
It works in Australian Rules Football and will work in NFL too. Get rid of the pads and watch players begin to protect themselves. When they are protecting themselves they won’t be using their heads and shoulders as missiles. Americans often watch Australian Rules highlights and remark that it’s crazy and dangerous. The medical results would actually reveal the opposite, it’s much safer. We have virtually no instances of brain injury, and I only use the word virtually because I cannot categorically say “none”. I’d love to see a competing league set up without pads, full contact, and see what happens.