Since reports were released saying that there would be a reboot of Suicide Squad, many have been speculating if the movie would reprise any of the original characters and actors. So far Margot Robbie is seemingly out (although there have been conflicting reports), and it looks like Will Smith now definitely not coming back.
Smith will not be returning for James Gunn's The Suicide Squad set to premiere in 2021. Variety reports Warner Bros is either going to recast Smith or replace his character with another one all together.
Since the success of Aquaman and Wonder Woman, DC looks like it's trying to step up their game, and adopting the motto of "in with new and out with the old," as many earlier DC characters are leaving and a few movies are being rebooted.
So far there has been no casting announcement for The Suicide Squad. Reportedly, Warner Bros and DC both wanted Smith and Robbie to return, but due to scheduling difficulties, Smith has exited the role.
As for Robbie, she is reprising her role as Harley Quinn in Birds of Prey (And the Fantabulous Emancipation of One Harley Quinn), but we just aren't certain if she will be cast in Gunn's reboot.
Both Deadshot and Harley Quinn were the two of the most popular characters in Suicide Squad, so it's a bummer if neither can stick it out for another film.