Earlier this year, it was reported that DC Films and Warner Bros. were developing a solo film starring Batman's first protege-turned independent vigilante, Nightwing. Since then, nothing else has come out regarding the film, though there is someone who's shown interest in portraying the grown up Dick Grayson.
Australian actor Dacre Montgomery, who made waves earlier this year by playing Jason Lee Scott in the Power Rangers movie, in addition to playing Billy Hargrove on Stranger Things, tweeted a photo (since deleted) of Nightwing, with no caption other than an ellipsis.
This could mean one of two things: that he's either auditioned for the role and landed it, or he's simply doing some social media savvy work to drum up interest. In the case of the latter, it's worked in the past, sort of; Ryan Potter of Big Hero 6 fame made a public case to land the role of Tim Drake, and got a very vocal fanbase to aid him in his efforts. (He later wound up getting the role of Beast Boy in the upcoming Titans series.) We'll find out for sure when WB makes an actual casting announcement.
Until then, the only Nightwing that fans will see in live-action will be Brenton Thwaites' interpretation in TV's Titans when it debuts in 2018.