During a interview with Guillermo del Toro at Comic-Con SHH asked the director about the Justice League Dark project that he's been developing. He was asked if this would connect with any of the other DC properties currently in development, like Constantine or Sandman. This was what he said,
“I’m still working on it. Sandman doesn’t figure in the Dark Universe. We have Deadman, we have the Demon, we have Swamp Thing, we have Zatana, we have Constantine, but DC and Warners have been very clear that they are trying to keep those properties separate so when the time comes they can unite them, once they know they’re quantifiable. Batman, Superman, Green Lantern… everyone eventually will come together. Right now, they’re allowing us independence.”
When it comes to the Constantine TV series that's coming out and how that figures into the equation he said,
“No, I had that conversation when the Constantine show was pitched. I said, ‘Do I have to have continuity with that?’ and they said, ‘No, feel free to continue the way you’re going.”
He added, “Swamp Thing for me is my favorite superhero of all times. I always like the monsters." That comment led him into talking about the Hulk, "I love the Hulk,“ which was followed by an update on the Hulk TV series that he was working on with Marvel. Unfortunately, he says that the show has been cancelled, and he thinks the reasoning behind is because they were having so much success with Mark Ruffalo’s version of the character in the movies.
That tells me that maybe they are actually planning that solo Hulk film that fans have been hoping for.