I think the beauty of that ending is that everyone can make of it whatever he/she wants, without drastically affecting the journey of the story/characters that preceded.
I don't see that it necessarily needs to be greatly significant. Just my personal view, a nod to Harry Grey, the real Noodles, and possibly Jill from Once Upon A Time In The West.
Leone had a wicked sense of humor and his words were preceded by "maybe just maybe...", indicating to me that he wished to keep some ambiguity.Ambiguity is very irritating to those who need to compartmentalise things but it's fine with me. It mirrors the world in which these gangsters lived and the book on which the movie was based.
According to Mickey Knox's autobiography, this gangster was Jimmy Blue Eyes.Knox: "Before starting Once Upon a Time in America, Leone got a rare meeting with the real but elusive head of the Mafia in the States — Jimmy Blue Eyes. Jimmy Blue Eyes avoided all publicity and was unknown to the public; as they say in professional circles, he kept a low profile.How Leone got the meeting with Jimmy is unclear. In speaking about the meeting, Leone inferred that he had arranged it with a lawyer who handled Mafia legal affairs, but I had the sense that this wasn't the whole story.Leone sat across from Jimmy at a back room table of an Italian restaurant in Brooklyn. Leone told him that he was going to make a film about gangsters in the 1920s. Jimmy listened, his eyes staring down on the table, never looking at Leone. When Leone finished, Jimmy spoke in little above a whisper: "You no makea dat movie."Leone quickly got the message and added, "My movie is about Jewish gangsters in the 1920s."Jimmy Blue Eyes slowly lifted his eyes to Leone and replied, "Dat movie you make." (Jimmy Blue Eyes had very dark brown eyes.)"
I believe that he eventually learned some English after Fistful.
why was the gangster with heavy accent speaking in English to the director who spoke no English?