James Wan recently revealed his plans that The Conjuring 3 movie will be set in the 80’s. Wan stated that if the previous two films (The Conjuring 2 (2016), The Conjuring (2013)) were set in the 70’s, The Conjuring 3 definitely should be set in the 80’s. Some of the best Ed and Lorraine Warren cases from that time suggests that the Demon Murder Trial case with Arne Johnson murdering his landlord Alan Bono might be the topic where the demonic possessed killed while under possession. Could be a good opening for the film since it is also a hit to the Warren’s success. Another case could involve The Haunting in Connecticut, but that might be too close to The Haunting in Connecticut (2009) film. The most likely featured film will include the Smurl Haunting where Jack and Janet Smurl were haunted by a demon in their home between 1974 - 1989. The house was haunted by three ghosts along with a demon who physically abused Jack Smurl while also sexually abusing both Jack and Janet Smurl.
James Wan said in a recent interview:
I do have something specific but I’m not going to say it. But I will say this - I do think Conjuring 1 and 2 are both set in the 70s, I think Conjuring 3 has got to be set in the 80s.