Suicide Squad was a box office hit, and a sequel was announced almost as soon as the first movie was released, but Warner Bros. isn’t fast-tracking Suicide Squad 2 the way they did Wonder Woman 2. The studio announced that Gavin O'Connor (Warrior, The Accountant) will write and direct, but they haven’t publicized an official production schedule.
According to various reports, Will Smith’s schedule is so busy that shooting for Suicide Squad 2 might not even happen in 2018.
But Omega Underground (via Screen Rant) recently reported that we can hope to learn more about casting and plot points in the near future. The aforementioned source said that Suicide Squad 2 production will start as early as March 2018, so the director has less than five months to complete the cast and scout for locations.
It’s safe to assume that Will Smith will be back as Deadshot. There’s also a good chance that Margot Robbie, who is starring in the Gotham City Sirens spin-off, is likely to return as Harley Quinn.
Jared Leto said that he was completely committed to his role as the Joker, although he obviously wasn’t happy with how the first movie turned out. But while we wait for Gotham City Sirens and the Joker/Harley spin-off, it’s possible that he’ll appear in Suicide Squad 2.
We should keep in mind that this is really just as an unconfirmed rumor. But it appears that the studio wants to continue to try new things, as evidenced by the numerous projects they have in various stages of pre-production (including a rumored Deathstroke movie with The Raid's Gareth Evans directing).