5. Justice League Dark
Though Warner Brothers has been hesitant about adapting films based on their first-tier properties, they have been known to greenlight films based on their lesser known characters (Constantine, Jonah Hex, V for Vendetta). Though the critical reception to these properties has been a mixed bag, it doesn't mean that it's not an avenue worth taking. There is, ultimately, less risk involved when adapting characters that general audiences may not be as familiar with. Yes, they won't make as much money as, say, Batman or Superman, but because they aren't as mainstream, a film's failure won't be seen as such a disaster for the studio. They can try new, interesting ideas, while spending less money than they do on their tentpole projects.
One such project was first rumored to be in development last fall: Justice League Dark. Guillermo Del Toro is attached to the project and gave an update at WonderCon in March, saying that he will begin working on the screenplay soon. The team consists of several of DC's supernatural characters, including John Constantine, Zatanna, Deadman, Swamp Thing, The Spectre, and Etrigan the Demon. These supernatural heroes handle situations that aren't fit for the traditional Justice League. It's easy to see how a project like this could work, and under Del Toro's direction, could be a huge hit with comic book fans. The man is very familiar with these characters and has a history of working with the supernatural (just look at his filmography). He is still waiting on a greenlight from Warner Brothers, and has stated that if there is a way to place this film in the same universe as Man of Steel, he'll do it. This film could even spawn a universe of its own, existing within the DCU but taking on its own stories, characters, and adventures.