Pure speculation, but interesting. I mean, we don't know what happened, even though people on other sites who are just as informed as us seem to.
If he has a lengthy contract, I don't see him leaving. However, I'd hate to think that's the only thing keeping him there. If it is, I don't know if we'll get the best Batman/Bruce Wayne. He's a professional and I don't think he'll intentionally do a bad job, but he may not fully be there if he wants out.
All true. But given the Sadfleck videos and memes, plus the poor box office for his latest movie Live By Night, as well as the general shambles the DCEU currently finds themselves in, I cannot help shake the feeling that Affleck is attempting to distance himself from the role little by little, especially given all the pressure on him to deliver an amazing movie AND performance in said movie. That's a lot of pressure so I'm not surprised he stood down from directing. I hope he stays on as the character, because he was one of the great things in BvS and has already surpassed Clooney and Kilmer in the "best Batman" hierarchy (admittedly not hard to do).