Nice topic. I agree with you 100%.

If they had filmed a third Godfather film, in say.. 1976, rather than waiting a whole 16 years after part II, the whole cast would still be relatively young and the audience would still feel like they were actually seeing a Godfather film.

Rather than this melodramatic nonsense of a dying family like we constantly see on AMC, FFC could've really set the most perfect trilogy of all time. Heck, they could even have added some Brando and Caan flashbacks in the third movie to make it more lively. The John Cazale flashback doesn't fit at all in the third film as it is and the story of Michael and Fredo seems left untold.

For this reason, a lot of people love the LOTR movie trilogy, due to it being filmed in one long stretch and released within a fairly short period of time. Well.. this is just a lesson to be learned in the history of movies.. I'll always be in debted to FFC and Mario Puzo for constructing a great story, but perhaps this issue will be solved in the future with other films.