Guillermo del Toro was at WonderCon this past weekend talking about his latest projects. Unfortunately I was unable to attend his panel but some information concerning his Dark Universe project has surfaced, thanks to Collider.
It was said that the movie bible has been completed and he will begin the screenplay soon with a writer to be announced soon. John Constantine will be the lead character recruiting others. There will be elements from Demon Knights. The characters' origins will be told throughout the movie. Other characters such as Deadman and Swamp Thing were mentioned plus the fact that del Toro's often stated his fondness for Etrigan.
We'll have to wait for more information.