Word comes from Variety who also states that Ben Affleck will stay on the Batman movie as a producer and as the titular character.
“There are certain characters who hold a special place in the hearts of millions,” Ben Affleck said in a statement. “Performing this role demands focus, passion and the very best performance I can give. It has become clear that I cannot do both jobs to the level they require. Together with the studio, I have decided to find a partner in a director who will collaborate with me on this massive film. I am still in this, and we are making it, but we are currently looking for a director. I remain extremely committed to this project, and look forward to bringing this to life for fans around the world.”
WB also commented in a statement: "Warner Bros. fully supports Ben Affleck’s decision and remains committed to working with him to bring a standalone Batman picture to life."
According to the report, WB and Ben Affleck are eyeing War for the Planet of the Apes director Matt Reeves to now direct the Batman movie. It's also said Captain Fantastic helmer Matt Ross is eyed to direct.
Update #2: Batman script could get a rewrite.
The Batman movie has been said to have been originally slated to start filming this Spring for a 2018 release. With Ben Affleck now stepping down as director, it remains to be exactly seen when production will kick off.
Ben Affleck has been evasive as of late in interviews regarding the Batman movie. At times Ben Affleck has confirmed that he is directing Batman, while in different interviews the actor seemed more indecisive. Affleck also recently lashed out regarding all the press Batman was receiving, while his latest movie, Live By Night, which recently bombed at the box office, received little attention.
Ben Affleck next stars as Batman in Zack Snyder's Justice League, out November 17, 2017.