***
The reason (most) people weren't satisfied with GF3 is because it really wasn't necessary, and was only made precisely because fans begged for something to "bring us to a close"; result, despite the reunited writing team of FFC and Puzo, it paled in comparison to GF and GF2, and is often dismissed by the most loyal GF fans as "a joke". They had to come up with a completely new story, and it didn't work.

Are they to keep making sequel upon sequel until someone decides that it's finally a "good" close? No, FFC did the right thing.
Michael Corleone is dead. Brando, Pacino & DeNiro have taken their place in cinema history. It's over. That is, I hope it's over.

Apples