In the spirit of speculating based on known movie characters, here's a theory for you: Michael had Don Altobello manage things in NYC until he stepped aside for Joey Zasa.
That's an interesting one, Woltz. He came in out of nowhere in III. He was Connie's godfather, which means he was close to Vito. He also was aligned with Zasa in his betrayal of Michael. Anyway, it's the best answer to a question that has no provable answer.
Best answer indeed
Wonder whether Don Altobello was an independent Don or was running the New York operation like a Corleone! muscle-in-reserve for Michael and paying tribute to Michael as well
