This rumor really isn't as far fetched as it might seem. According to Forbes the caped crusader may have a cameo toward the end of David Ayer's Suicide Squad. This of course makes the most sense then part of the film may take place in Gotham amongst other locations. This would be nothing more then a cameo of Batman played by Ben Affleck which would set up his own solo film featuring The Joker (Jared Leto). The site goes onto say the Batman solo film "will take some inspiration from Frank Miller’s comic book series The Dark Knight Returns — the third issue of which is a story about Batman facing off against an escaped Joker. I’m also told that Gotham City Police Commissioner Ellen Yindel (who replaces James Gordon during the comic book story) is planned for inclusion in the film." This of course was already mentioned by Forbes last week on the Shanlian on Batman podcast.
Suicide Squad hits Summer 2016