DC has seldom shied away from swapping out directors for projects (look no further than the issues that have plagued The Flash’s solo film for evidence of that fact), so bringing someone in to take the baton from David Ayer doesn’t seem entirely unrealistic.
Another possible course of action for Warner Bros. and the DCEU would be to just continue the development of Gotham City Sirens without David Ayer.
If the film still moves forward, Ayer could go on to work with Netflix on Bright 2 while the DCEU finds a new director to step in and take on the female-centric supervillain movie.