... who would have been the one to beat him? I can't see fragile Floyd Patterson's chin holding up, and Ingo's just not good enough IMO. Would it have taken another 5-6 years, until Liston was on the scene, for a gradually-getting-older Marciano to finally taste defeat?
Marciano's style wasn't suited for longevity. Still, I think he had enough in him for 2 or 3 good fights left, and perhaps a reign until 1957-1958
The first thing to go with age is speed, and the last to go is power. So I think Marciano would have outwilled and overpowered everyone, and would have lost to a young Muhammad Ali.
Patterson would have never beaten Marciano. He fought Liston twice and got KO'd both times in the first round for his efforts. A fight with Rocky would have likely ended very similar.
Only people who don't know verry much about the era. His 50th fight would almost certainly have been against sombody other than Patterson. Nothing is surer than that if he hangs around he is going to loose to sombody eventualy. My best guess is that he would have got past Patterson but not made it as far as Liston.
Those people are engaged in ahistorical, anachronistic and simply false conjecture. In point of fact, Patterson was not even an established serious contender at heavyweight when Marciano decided to retire, and certainly wouldn't have been next in line for a title shot. Marciano's reasons for retiring are well-documented; he had lost his vigor for training, he had recently learned that his manager, Al Weill, had nicked money from him for the Cockell fight, and he was purportedly having significant back problems. Floyd Patterson was not seen as the heir apparent for the heavyweight championship in early 1956, and it was reportedly the case that Patterson's quite-cautious manager, Cus D'Amato, deliberately waited until Marciano was out of the picture before making his move.
It is very hard to pick his next 3 fights because he had cleaned out the decision and people who were doing well around the time of his retirement had either been beaten by some one Marciano had beat or had already lost to Marciano One thing for sure, Patterson would not have been his next fight. If Marciano didnt retire then Patterson Moore would probably not have happened in '56 as they wouldnt have had to fight for the vacant title. Does Patterson still win Ring Fighter of the year? I doubt it. Bob Baker coming of the Nino and 3 wins over Layne win at 45-6-1 would have been a very viable option in early '56 assuming he dosent have the Jackson fight and has the Marciano fight in its place. This would be Marciano's 50th win. No idea who he fights next he could probably fit two fights in then he could have then fought Pete Rademacher for his pro debut the same way Patterson did and would have beat him in probably a similar fashion.
Marciano also had a deteriorating back and that was one of the reasons he retired. I think at times he could not even bend over to tie his shoes. He said he had a couple good fights left in him when he retired but that was probably about it.
Marciano was clearly too smart to hang on too long ... on any given fight past Moore his skin could have busted up and he could have lost to a lesser man ... however putting that huge issue aside I can see him hanging on till early 59 when Sonny would have been way too much ...
Obviously Marciano didn't have a style for longevity, plus a combination of age & "wear & tear" would be deteriorating his body, but considering the way Rocky always trained like a spartan, i presume he could rule until Liston is matured enough to stop him, in '58. I don't think Patterson has the chin or durability to beat Marciano, taking into account styles.
The Rock had lost the desire...his back was bad...Al Weill was skimming money from the Cockell fight...and with his style.. longevity is certainly not in the cards...he had beaten the top contenders...and he got out in April of 1956 before his powers had left him...
I dont think it would be Liston or Patterson who would have done it. My money is on Machen or Folly who were around during the prime Patterson years. I think they beat Marciano in the 56-57=58 time lines here. Assuming Rocky makes it that long Liston around 58-9. 5 years waiting around for Liston seems a long wait. Marciano would be 37-38 himself if he made it to Liston and I cant see that.