Affleck will reportedly team up with Geoff Johns, DC Comics' chief creative officer, to write the script. Johns is a DC legend at this point, having written for many of the company's premiere titles (Batman included) as well as writing for TV's Smallville, Arrow, The Flash and the new Supergirl.
The next Batman stand-alone film is a long ways off, though. First, Batfleck will make his debut in Batman v. Superman: Dawn of Justice in early 2016 and will later appear in Justice League in 2017.
Affleck is also set to start production on his next directorial project this November, an adaptation of the Prohibition-era crime novel Live By Night, set in Tampa's Ybor City neighborhood.
Look for more Batman news to come out of Comic Con in San Diego this week, where Affleck is expected to make an appearance.