I think the majority thought he should have regained it in Charles-Walcott 4. I doubt there would be a 5th fight and Charles started fading at this stage. If Walcott and Charles are at their best I don't really see them losing to anyone Moore included but Archie ofcourse has a punchers chance and was going strong when Walcott/Charles had lost form/retired
Throwing out some idle thoughts here. Layne and Matthews paid a heavy price for Marciano being in the way. LaStarza, Layne and Cockell were all still in their 20s when Rocky hung them up. Matthews did not take a beating from Marciano, but got put out by two hooks. That Cockell went three for three against Matthews, twice in Seattle, gets overlooked. Don did outpoint LaStarza immediately after Rocky beat up Rollie in their title rematch, but I can't dismiss the trilogy over Matthews so casually. Harry would never lose again. Joe Louis does get one final title shot, but can't get by either Walcott or Charles. I do think that Ezzard, being over seven and a half years younger than Jersey Joe, does win a fifth rubber match if they square off yet again for the title. Head to head, Ezz also has Moore's number. Archie can't get to the top with Charles in the way.
I think Walcott would have been a strong factor and Charles would have also cleaned up on most of the the Heavyweights. Archie was a strong presence and would have done damage to the division but I don't think he could have beaten Charles or Walcott. Also many fighters that Marciano ruined may have become a factor such as young prospect 6"4 Carmine Vingo, Rex Layne, not sure how Lastarza or Matthews would have done vs Charles or Walcott but I think all of these fighters mentioned would have had better longevity had Rocky Marciano never been born.
The abscence of Marciano would have made for an exceptionally week era. The public may very conceivably have seen a 5th bout between Charles and Walcott, with both being past their best.. Men like Moore and Lastarza would have had a real live chance of winning the title.