Turnbull, I think you're competely off on this. The Mafia was in its heyday in the 40s and 50s. What is this small pond you refer to? The NY families have always dominated the American Mafia and they maintained close ties with Sicily and other ethnic crime organizations. It was no small feat that Vito was able to summon organized crime figures from across the country to the "Cosa Nostra" meeting.

In addition, I didn't infer that Michael wanted to be organized crime's emperor. He conducted his affairs in shark infested waters and took appropriate actions to protect those affairs. When business opportunities opened up, he attempted to take advantage of them. Pensate!