Screenwriter Leigh Whannell is currently in Austin at SXSW premiering his latest film, THE MULE, but while there he had occasion to talk about INSIDIOUS 3 with Screen Rant.
Whannell confirmed what we already probably suspected, which was that the Lambert family will not be the center of the film, their story has been told, but Specs and Tucker - the ghost-hunting characters played by Whannell and Angus Sampson - will indeed be returning to provide some levity. Whannell went on to tease that "maybe even" Lin Shaye will return as Elise, which I think we can interpret as Lin Shaye will definitely be returning.
Jason Blum is once again producing the new INSIDIOUS film, the script for which Whannell has completed. No director has been announced yet, but all signs point to James Wan not being behind the camera this time around. It's set to be released on April 3, 2015.