According to Justice League producer Charles Roven, Ben Affleck is "certainly planning" on starring in filmmaker solo Batman movie right now.
Justice League is Affleck's third time portraying the Dark Knight - he also starred in Batman V Superman: Dawn of Justice and cameoed in Suicide Squad - and the actor's comments during the film's press tour have only added fuel to the fire that his departure is imminent. Affleck was originally slated to write, direct, and star in a solo Batman film, but he stepped down from the writing and directing duties after a long pre-production process. War for the Planet of the Apes director Matt Reeves took the directorial reins from there, based on the initial assumption that Affleck would still star.
Roven is attempting to keep that assumption afloat. In an interview with CBM, Roven says he believes Affleck intends to portray the Caped Crusader for Reeves:
“I’m not producing that movie, Matt Reeves is working on that, but I do work with Ben, so I know that he’s certainly planning on starring in that film, but I don’t know what the script is. I’m not producing that movie, so I’m probably the wrong guy to ask.”
That's not exactly a confident endorsement from Roven, and will likely do little to stop speculation over Affleck's future in the role of the Caped Crusader - all the more so, considering that Affleck himself has said that he's still mulling whether or not he'll star in Reeves movie and is already thinking about his exit from the DC cinematic franchise.
If Affleck does indeed move on after Justice League, there are apparently plans in place, as Matt Reeves reportedly has another actor in mind for the new Batman. There's a long tradition of recasting the character, even within the same continuity; Val Kilmer and George Clooney were ostensibly playing the same version of the character originated by Michael Keaton in Tim Burton's Batman. While he debuted in the divisive Batman V Superman, Affleck's Batman has proved popular with many fans, and his departing after such a short tenure - and before he even gets a solo adventure - would feel like a missed opportunity. However, these shared universes are bigger than any one actor, and Batman is in many ways the centerpiece of DC's universe.
Put simply: there's no way the DC movie universe is going to go Batman-free for any significant amount of time, Affleck or not. Fingers crossed, a firm update on the situation will be arriving sooner, rather than later.