As naive as this sounds, I dislike what I see as the forcing of a Justice League Part One film into existence by 2015 simply to compete with Marvel, but if it’s going to happen without most of its characters pre-established in their own films (Green Lantern notwithstanding), I think the film should start out as a sort of big budget Sam Spade mystery with J’onn J’onzz/Martian Manhunter at its heart, evolving and growing in scale as the threat worsens and he finds and recruits the others. Why? Because for most of the modern Justice League’s existence, the Martian Manhunter has been the glue that holds the team together. Unlike the others, whom we’re used to seeing in solo adventures, I suspect that Manhunter is most likely to be seen collaborating with someone else, anyway. As a detective in his human form in a Detective Comics property, he is the most logical choice to introduce first, discovering clues to a much larger threat and realizing, in his outsider’s wisdom, that he needs the help of other metahumans and superheroes. There is a lot more to this than I can include here, but this is the way that I believe the film can avoid confusing the larger audience and alienating the fans. The film should start by focusing upon a single character that it can make its own, one slightly less burdened with the iconoclasm and expectations that could make introducing everyone at once seem lazy and disrespectful. It would also make the eventual collaboration more meaningful by presenting the need for it through fresh, slightly more vulnerable eyes as opposed to having Superman, for example, suddenly decide he has to team up with everyone for a fight that we know he could probably take on alone. In fact, though I realize how unlikely this is, if it were me, I would save a character like Superman for the climax, much as he was saved in the JLA Year One story-line.
The Batman Reboot will probably be more tricky since most fans feel he has already been adapted to film as well as he could be in ’s Dark Knight Trilogy. Those films' stand-alone approach has been both a blessing and a curse, focusing our attention on Bruce Wayne’s struggles without the distraction of looking for hero cameos and such, but also taking away something very valuable to build upon that Warner Brothers is probably looking for in Man of Steel. The only way I can see a Batman reboot having something new to offer is if it dares to explore the more sci-fi elements of the Batman comics that have yet to be adequately translated onto film. I also think that including the Robin character is going to be essential to convincing general audiences that they’re not just being fed a lesser copy of the Nolan films, but I don’t think this means that Robin has to be a full-fledged hero by the end of the first movie. His origins as Dick Grayson can be retooled to be part or even the basis of the first film’s plot from start to finish, making his integration far more organic than it was a third of the way into Batman Forever. His status as a 13 year-old boy instead of a high school or college kid, for example, could be a way of servicing the themes of Batman’s origins without actually retreading them again. Ultimately, he serves as a new element that evolves from film to film and brings out different traits in Batman, complimenting the central character instead of distracting from him.