Joseph Gordon-Levitt is off Sandman. This pretty bitter news came straight from the actor/director/creative whirlwind himself on Facebook:
So, as you might know if you like to follow these sorts of things, a while back, David Goyer and I made a producing deal with Warner Brothers to develop a movie adaptation of Neil Gaiman's SANDMAN. Neil himself came on as an executive producer, we hired the excellent screenwriter, Jack Thorne, and we started in on the ambitious task of adapting one of the most beloved and boundary-pushing titles in the world of comics. I was pleased with the progress we were making, even though we still had quite a ways to go.
Recently, as you also might know if you like to follow these sorts of things, the sorta "ownership" (for lack of a better term) of the Sandman material changed hands when Warner Brothers shifted the entire catalogue of Vertigo comics (an imprint of DC) to their subsidiary, New Line. And a few months ago, I came to realize that the folks at New Line and I just don't see eye to eye on what makes Sandman special, and what a film adaptation could/should be. So unfortunately, I decided to remove myself from the project. I wish nothing but the best for the team moving forward.
I'd like to thank all the great people I've had the opportunity to work with on this one. I've had a blast with and learned a ton from David and Jack. Niija Kuykendall, Greg Silverman, and everyone at Warner Brothers have been fantastic, as have Geoff Johns and everyone at DC. And it's been a particular privilege as well as a rocking good time getting to know Mr. Gaiman, whose generous insights and masterful work have certainly convinced me that the Lord of Dreams and the Prince of Stories are one and the same Endless pattern."
That's pretty sad news for anyone who has been following the gestation of the project, which certainly sounded like a very interesting one to be coming from a major studio. JGL is pretty clear on what it wasn't working, with the transition to New Line causing some kind of friction for the filmmaker. He was on board as a producer but everyone was hoping that he would also play the central part of Morpheus - he has the presence and clearly a lot of passion for the project.
As of right now the script is still being written, and there's no confirmation on director, cast or release date. We wouldn't be surprised if this particular dream never comes to pass.