Take this with a grain of salt and there's no official confirmation yet (until announcement), but word on the grapevine's already spreading that two of DC Comics' most important heroes and icons will be starring together in their own feature team-up film, and COULD be announced during the WB Panel at the San Diego Comic Con.
In anticipation and build up for a shared DC Movie Universe, it looks like The Hollywood Reporter is picking up reports that the next big DC film may be in fact a Superman/ Batman film, where Henry Cavill returns to the big screen as Superman and teams up with a new actor playing Batman. Zack Snyder of course is set to return as director after Man Of Steel, with David S. Goyer penning the screenplay.
Now this is all rumor and hear say at the moment, and the Warner Bros. Panel at the San Diego Comic Con is currently happening. However, given the impending nature of reintroducing Batman into a DC Movie Universe with Cavill's Man Of Steel, this makes perfect sense and is a good lead on to a potential Justice League film. The idea was also teased back in 2007 with a "Superman/ Batman" poster seen in a post-apocalyptic Times Square on Will Smith's "I Am Legend", so the "World's Finest" teaming together on their own flick isn't exactly a new idea. In fact, before the Superman reboot that is MoS happened, this was the plan. It would be a wise move by WB and DC Entertainment too, since it introduces A NEW Batman outside of Christopher Nolan's epic Dark Knight Trilogy of films, and sets the stage for the inevitable rise of a JL film. There's also the rumor of a Flash film for 2016, then JL on 2017 (via Bleeding Cool). Still, let's wait for official confirmation from the SDCC.