This is one of those stories where someone's secret 'sources' are possibly just pandering to the dearest wishes of fandom. Tread carefully as we proceed then, since there's obviously no official basis for the following information. But a reasonably credible-sounding rumour emanating from Forbes suggests that Ben Affleck's Batman may show up for a cameo appearance in DC/Warners' developing Suicide Squad movie. That in turn, the story goes, will lead into a standalone Batman film in which Affleck will face off against Jared Leto's Joker.
According to Forbes' intel, Batfleck will appear in an "in story" Suicide Squad scene (presumably as opposed to a scene where he appears brielfy on video monitors, as others have suggested will happen). Said cameo would focus on "certain circumstances involving the Joker", which remain un-spoilered.
In this version of events, there then follows a solo Batman outing in which the Joker is the main antagonist. Word on Forbes' street is that this will be some sort of adaptation of the third chapter of Frank Miller's seminal graphic novel The Dark Knight Returns. That comic sees the Joker waking from a catatonic state, escaping from Arkham Asylum, killing an entire talk show audience via the medium of deadly balloons, and going on the rampage at a fairground. It also features a new Gotham police commisioner in Ellen Yindel, who we're told will appear in the film.
Is this all to be believed? We're wary, as always. Forbes actually take the time to say that this may even be deliberate disinformation designed to throw Dark Knight detectives off the trail of what's really happening. But it doesn't entirely sound unlikely either, especially given the Miller echoes in what we think we know so far of Batman V Superman: Dawn Of Justice.
Whatever, a solo Batman film is some way off yet, and significantly doesn't even have a pencilled-in release date on the decade-long DC/Warner schedule revealed late last year.
David Ayer's** Suicide Squad** however, starring Leto, Margot Robbie, Will Smith and not Tom Hardy anymore, is out on August 5 next year. So we'll see if Affleck shows up then...