Boss Jackie Aprilie is actually in the movie as a teenager too. I don't know if many caught that.
I'd like to see who became Boss after Moltisanti and how Jackie eventually ended up boss.
I don't think either Dickie or Hollywood Moltisanti were actually the boss. My impression was that they were more Ralphie level guys, capos, who had their own crew. Same with Johnny and Junior. It was never clear what the exact relationship was but Johnny, Junior & Dickie were definitely equals and rivals. I don't think it was clear who the boss of the family was. In the opening monologue Chris refers to his father as an associates of the DiMoe crime family and a great earner, better than the made guys, indicating at that point he's not even a made guy.
Would also be very interested in the path Artie Bucco took. As a teenage he appeared to be Tony's closest friend & associate and right there with Tony & Jackie on the Mr. Softie raid. Unlike Tony his family isn't in the mafia and clearly does not approve of Artie's friendship with Tony.
Biggest question is how did Tony and Jackie rise above Silvio, Paulie & ***** who were older and already active in the family. When the Soprano's opens Tony and Uncle Junior are rivals to succeed Jackie as boss at least in Juniors eyes. My guess is the next chapter would deal with the rise of Johnny & Junior and the development of Tony. i.e. the poker game robbery & the hold up that went bad that Tony didn't show up for. Tony B was reference in TMSON but never appeared.
I could see at least two more movies to feel in the blanks.