It would be tough to do now, because Pacino and Duvall, and Talia Shire, are now too old to play Michael, Tom and Connie in the 1960s.

It would be good to see exactly what was the resolution of the Michael-Tom dynamic. Clearly, that was a major conflict that FFC and Puzo were setting up at the end of GF II. There are several key lines of dialogue where the loyalties of Tom Hagen are called into question.

Tom is obviously a brilliant and highly resourceful manager himself, so he would be a formidiable adversary for Michael if he ever decided to break off from the Corleone family. Whether he ever would or not, would be a huge quesion to be answered.

Perhaps, "The Godfather Returns" is the first example of officially-sanctioned "Corleone Family" derived material - much in the fashion of Star Wars, Star Trek, etc., where complete lines of books, etc. have been based on the canonical characters, concepts, etc.

There are hundreds of Star Wars and Star Trek books, but the only ones that "really count" are the officially released movie versions - those are considered absolute canon. All the peripheral stories are considered "alternative realities."