An original Invaders flick? That would be sweet.
Or they could do a movie "The Human Torch vs. The Sub-Mariner" have it be good and all, but harken it back to the 40s and 50s horror movies "Godzilla vs. Mothra" and stuff like that. Look at the Marvels mini-series, when Namor and Torch first appeared, they were feared more than death itself, having a movie where they fought over 1930s/40s New York would be sweet. Namor could marshall Atlantean troops while Torch ushers forth the fear of terrible new mechanical beings taking over. Awesome stuff.