Chris McKay is the director behind The LEGO Batman Movie, and as of now he's currently attached to direct the Nightwing movie for the DCEU. A rumor has apparently been floating around that Zac Efron has been cast as Dick Grayson, but McKay has come out to debunk it.
Though I think Efron is a pretty good actor, McKay has been vocal about casting an actual martial artist for the role of Nightwing. Of course, Efron could always train to do those stunts, but I have a feeling there are already several legit martial artists out there that would be perfect for the job.
With WB focused on pumping out Aquaman, Shazam!, Wonder Woman, and Birds of Prey, Nightwing has unfortunately been put on the backburner. We don't know when McKay will be starting production on this movie, but rumors say that if he decides to direct the Dungeons and Dragons film, Nightwing will be pushed even further back.
Besides Dick Grayson, there are also a bunch of other movies that the DCEU is said to be working on. We still don't have a release date for the Green Lantern Corps. film, but we do know that the Flash solo movie has already found a duo to direct. Not to mention, there's a rumor going around that Man of Steel 2 is aiming for a release in 2020.
No official release date has been announced for Nightwing, but we could get the movie out after 2020.