If Tyson followed the route that Holyfield did when he beat Tyson then he may have fought and beat Moorer (ala Tua did ) and Vaughn (How the hell did I get a title shot) Bean. He may then have fought Lewis and lost probably like he did against Holyfield. Strong early and then blow out. In the rematch he would then try and bite Lewis ear/knee and shame himself and go off the rails again.
Holyfield would have beaten fighters but would have been a lot older by the time he fought Lewis and lost convincingly with no rematch.