Updated August 6, 2019: Atomic Blonde director David Leitch says that the previously reported sequel to the 2017 film may arrive on an unnamed streaming service rather than receiving a theatrical release.
I think there is [still talk of a sequel]. A streaming service is into it. I don’t know all the details," Leitch told SlashFilm. "I was a work-for-hire on that movie, but at the end of the day, Kelly McCormick – my producing partner and my wife – she will be involved, I’m sure, as a producer. That’s how I got the gig in the first place. We’ll see."
This seems to imply that while the film may come to fruition, Leitch himself may not be in the director's chair. Leitch did not name the streaming service that has reportedly expressed interest in the film.
Original Story: Atomic Blonde's lead actor/producer Charlize Theron has stated that work on a sequel is already underway. During a presentation last week at San Francisco's Castro Theater promoting her new film Tully, Theron spoke about her work on Atomic Blonde and preemptively announced the sequel news.
“We’re working on a sequel," she said (as quoted by IndieWire).
Atomic Blonde was a re-named adaptation of the Oni Press OGN The Coldest City by Anthony Johnston and Sam Hart. Johnston wrote a prequel with artist Steven Perkins which was released to coincide with the Atomic Blonde movie.
It is unknown if this film sequel will be an adaptation of that story, or an original story.