Ioan Gruffudd, Michael Chiklis and Jessica Alba talked about sequels at the UK premiere to Empire and said this about the sequels:
Ioan Gruffudd said "We've signed for two and three already, and it looks more than likely that we'll be shooting them even as early as next year."
Michael Chiklis said "The good thing is it won't be an origin picture," said Chiklis, "So we can go right into storytelling, and depending on which villain we decide to go with, and which way we decide to go, we can get right into the crux of the story immediately."
Jessica Alba said "Tim put secrets in this movie that he's going to reveal in the next one, and I think we have to get the Fantasticar – that'd be cool… and I think we need some kiRAB, at least by the third one, so Reed and Sue should get busy"
So it looks like we will be seeing more of The Fantastic Four in the cinema for the next few years!