In all honesty I do not know if it was ever off track, but a few sites are reporting it as fresh news (even though Charlie Jane Anders wrote about M. Besson’s adaptation a few years back) and since I will take any excuse to mention Valerian and Laureline, one of the greatest and most influential bd series ever, here is the information.
Dane DeHaan and Carla Delevigne have reportedly been cast as the leads in Luc Besson’s adaptation of Valerian and the City of a Thousand Planets.
Just some background. Created by Pierre Christen and Jean-Claude Mezieres, Valerian and Laureline are Spatio-Temporal agents who protect the timeline against various threats. Their adventures, translated in many languages, have covered some twenty-two albums (depending on which language you collect them in), as well as a couple of non-fiction books, been serialized in many magazines throughout the world, have been (loosely) adapted into the animated series Time Jam: Valerian & Laureline, episodes of which you can watch online (easy to find, was on Hulu a while back, on Crunchyroll, etc.). Plus elements of the series have appeared onscreen (unintentionally) in various Star Wars movies and (intentionally) in The Fifth Element (M. Mezieres did some production or concept art for the film).