Wiseguy2000, I know GF4 is gonna be made, don`t ask me why, but I certainly know. I have that feeling and that`s it. And about a happy ending, let me tell you it could not be in that way. The GF4 script is written by Mario Puzo before his death and Paramount Picture has it, Vincent is a bad Don and is gonna get into drugs business against the family rules, I think the movie could end with Vincent in jail and the Corleone empire falling down, it would be a nowadays Cosa Nostra story, you know that happened in the real life and I wish it would not have happened. there is another reason. The Vito`s phrase "Drugs will destroy us in the years to come" has to come true, and Vincent will be the one in charge to take the family to the ruin, there is a rule.
1-The first generation will build the empire(Vito)
2-The second one will keep it and make it stronger(Michael)
3-The third one will fail and take the empire to the ruin(Vincent)