I personally feel as though we need to move away from Michael in order for a fourth movie to be succesfull. Not that I don't love all the movies but theres only so many movies you can do that focus on the same character every time. I think we need to look more into other parts of the Family. Me i'd pick the time period when the Corleone empire was getting going before and during the Five Family war of the 30's. I think DeNiro can still do it, and i'm not sure if Bruno Kirby is totally out of the question either the only problem being he is that he isn't really heavy. I think there is a ton of plot in that time period and of course it would re-introduce us to the DON which is what we all really want. I'd also like to mention what a testament this is to Marlon Brando's performance that its truly the lasting image of the Godfather movies and really a lasting image on American film. I don't think any character in any movie has had the effect in that of the one of the DON he is the one that keeps me coming back for more.