According to Star, Suicide Squad Sequel Still In The Works
According to Joel Kinnaman, who played Rick Flagg, the sequel’s script is still being worked on, and shooting may begin in summer 2018. Since he is an actor he know little of the production, and whether he will be returning. He thinks he will definitely come back for it. The only cast members that may have multi-picture deals are Viola Davis, Margot Robbie and maybe Will Smith.
There is no director attached, the latest was that Mel Gibson was offered the position, the lack of confirmation may indicate he said no.

Image via Female First
“Ultimately, I’d love for David Ayer to direct it, but if he doesn’t want to direct it then someone who is great with character and that’s able to ground the story and maybe put these characters in a more normal situation. It would be really interesting to see these crazy characters interact with regular people as well.”
The film does not have a complete script yet, and a director is not attached. Basically, it is still too early to know what is to become of this film.
Gotham City Sirens is also still in the works, with Margot Robbie and David Ayer the only talent attached. Although, Josh Gad has been teasing he may play the Penguin, chances may be for Gotham City Sirens.
Source: THR.