Re: If Ali didn't come back to boxing.
Very likely Foreman would have dominated the rest of the decade. Much would depend on how he handled his title reign. Had he remained active and concentrated on perfecting his craft, he might have pulled the skills of young George and old George together, in which case he could have been dominant for a very long time. Title defenses against Quarry, Lyle, and Shavers could have been great fights. As a fully developed, mature, and confident champion, Foreman probably would have successfully defended against Jimmy Young, and maybe even Holmes, who would have been the stiffest test for him. When you consider that George regained the heavyweight title over twenty years after he lost it, and with a ten year layoff, you really have to wonder what might have been.