Fantastic Four screenwriter Simon Kinberg is hinting at what might be in a possible sequel: "[W]hat is interesting is that we were talking about that when we working on the first movie, and we thought about the franchise as a saga," he told Now Playing Magazine.
"We thought, 'Where does this saga go after the first movie?' And you will see that it is not just an origin story of the Fantastic Four; it is also an origin story of Dr. Doom, and it is not until fairly late in the first movie [that] he fully becomes Dr. Doom. And there is a lot of space for him to grow in futures films, and I am sure they will want to bring in other villains because all of these franchises do, but I have a feeling he'll be to Fantastic Four what Magneto is to X-Men."
Regarding Galactus, Kinberg said: "You know probably better than I what audiences are willing to get into. I would imagine it is possible. I would imagine the Fantastic Four franchise will do what the X-Men franchise [does] – get bigger and bigger each time out, ideally. And certainly Galactus will be as big as you can get."
Read the entire interview here.