It probably won't even happen. Tyson has ulcers, and recently suffered a flare up that delayed training and the fight's date. My dad suffered from ulcers and doctors were constantly in a scare that he would get a perforated intestine wall. At 65 that was actually what took him out, a fissure killed him in less than a week despite the doctors rushing for an emergency surgery, and he wasn't training to receive punches in the abdomen. When you are old, and Tyson is 57, things take significantly more time to heal, and the intestine is one of the slowest healing tissues in the body, I was told. Too many acids, bacteria, etc. circulating there. No doctor worth their medical title will ever let him train with an ulcer, much less fight.
And the worse of it all, I suspect that it is because of abuse of nonsteroidal anti-inflamatory medicine like Ibuprofen, Advil, and Naproxen. They are usually the first thing forbidden to chronic ulcer sufferers because they cause new ulcers and worsen flare-ups. They are overall really bad for the intestines. My guess is that Tyson's training has put him in a lot of pain and the painkillers gave him this ulcer. He is fantastic and has an extraordinary physique for someone his age, but no one is immune to old age.
I don't know, but if I had a gun and he was unarmed, I still wouldn't take a chance trying to take on Tyson. He may be getting old, but he's still a scary beast of a man.