Cinemablend is reporting producer Peter Safran (producer, The Conjuring, The Conjuring 2) will do something different with the The Conjuring 3:
“There are some [cases] that maybe aren’t as well known, but they spent a fair bit of time researching and were part of [them]. Clearly we can’t do another haunted house movie, right? We can’t do another supernatural possession in a house, with a family in peril. Right? So, it’s got to be something different than that, I think.”
While there is still no release date for the film, nor story idea, Cinemablend speculates there could be werewolves or other creatures of the night featured in the film. The Warrens, after all, do have a good investigation history.