Originally posted by DARKLORDCAEDUS
Nice idea, but no. If Galactus is some sort of cloud, What makes you think The Celestials won't be something like that. Second, The FF and The Celestials never even fought in the comic book.I don't think they should do a third. The Galactus/Silver Surfer storyline is perhaps the most interesting one that they could do, and they didn't do it to its fullest potential (though it was leagues above the first film).
First off, there will be a third. The box office is looking big enough that they will continue.
Second, since they cannot top the Galactus storyline for big significance, it is logical that they should pursue this to it's outcome; him being repulsed from Earth should draw the attention of other cosmic powers. Maybe the Celestials didn't first appear in FF, but as they are kin of sorts to Galactus, they should be able to follow him in appearence. It would also be an opportunity to introduce the Watchers, as they are the opposites to the Celestials. Unlike the Spider-Man & X-Men film series, FF has established extra-terrestial powers within their universe. The door is wide open for lots of alien Marvel creations to show up.
Third, why would the Celestials and Galactus appear in physical form in FF3? Because the rule of sequels is to get bigger each time out, and give the audience something they haven't seen yet. Think back to the original Star Wars Trilogy; The Emperor was held back until ROTJ, after just being mentioned in ANH and glimsed in a shadowy hologram in TESB. We were teased with shots of Galactus' shadow in that cloud in FF2; it would fit that he return and show himself in a humanoid form in FF3.