A sequel is currently in the works for David Cronenberg's “Eastern Promises," that's what the 2007 film's screenwriter Steven Knight has told Collider as he was promoting his upcoming film “Serenity,” with the sequel will probably begin production sometime in 2019.
“It is like fishing, where you leave it out there,” says Knight. “And it’s been out there for a while. It went through permutations in the sense of, how do you follow Viggo? We’ve been through that and we’ve moved on and now we’re in a position where I will say ‘watch this space,’ we’re close to getting into production.”
It would appear that the Cronenberg will not return. In addition, the sequel include Mortensen, but he won't be the lead, a "major actor" is being sought to take the lead.
Also, because Russia has been so much in the news, Knight reveals there will be political undertones:
“[The script] changed a bit,” the writer said. “It changed quite recently as a result of events in the world. The topicality of the Russia thing. I’ve adapted it to reflect recent events.”