I wish he still closed the rivalry with Norton by establishing a trilogy in order to give the public a definitive answer of who is better but what we got was highly controversial lmao Otherwise yeah, it would have been a perfect end to a stellar career.
Maybe the Neurological damage to Muhammad Ali's career would have been minimized, both Ali and Joe Frazier by this time were damaged fighters in one way or the other. Sure, it benefited the boxing fans and fattened the pockets of the fighters but in the end they were the ones who suffered.
If he retired after Manila. There's no damage from Shavers, Norton, Berbick Spinks Twice, Evangelista , Dunn, and Holmes.... Nine fights usually means hundreds of rounds of sparring to prepare for the fights. And where Ali was at the end of his career,with lost physicality and reflexes he was taking much more punishment during the sparring sessions than some of the fights. Without all that extra damage, it's quite possible Ali would've been the ambassador of the world. Imagine, a wised Ali , no longer tied into the rhetoric of the N.O.I with the ability to express himself of his youth. Good will ambassador of the World.
If they are completely okay - and I hope they are, I think the luck factor is on the side of the two examples you gave - their being more the exceptions to the rule. I guess they’re might be a correlate between iron chins and suffering little or no notable effects from boxing. Ali has a great chin but it didn’t have that completely impervious vibe to it like some others - Chuvalo, Cobb, McCall etc. Ali could take it but you could definitely see him feel it on many occasions - as we’ve all often said, he had terrific recuperative powers. Though sadly, another well chinned fighter, Joe Bugner, who fought into an advanced age, is now in care due to the cumulative effects of his taking punches during his boxing career. For a good period post career, Joe was fine, still highly articulate and sharp - seeming evidence that he had escaped any ill effects and going to be fine into his later years. However, in more recents years he took a sharp downtown, and losing his wife of many years, Marlene, during that time may or may not have exacerbated his mental decline.