WARNING: The following contains major spoilers for The Conjuring: The Devil Made Me Do It, now in theaters and on HBO Max.
The Conjuring: The Devil Made Me Do It definitely feels like the end of a trilogy, especially as director Michael Chaves didn't opt for a post-credits scene to continue the story of paranormal experts and demonologists, Ed (Patrick) and Lorraine (Vera Farmiga) Warren. It concludes with somewhat of a happy ending as the couple spend time together in a gazebo after ensuring that Arne Johnson doesn't get the death penalty for murdering his landlord.
However, the movie sets up intriguing threads for a possible sequel to continue expanding the Conjuring universe.
THE DISCIPLES OF THE RAM
This is the sinister cult we saw in the Annabelle series that got Janice to officially embrace her identity as Annabelle and push a demon into the doll. They're mentioned to the Warrens once more here as masters of the dark arts, performing rituals and inspiring occult movements. Isla actually studies them, and their Satanic totems would go on to help her become the Occultist. As a result, seeds have been sown where a follow-up can have the Warrens pursuing them.
They can become the Thanos of this universe, with relics, books, power and influence at all levels in society. To make it worse, they have reach all over America from Connecticut to Boston, getting people to hide totems and place curses. They're definitely tempting to these weak minds, as seen in The Conjuring: The Lover comic. Thus, the the Warrens should want to get these cultists out of the way so another witch like Isla doesn't arise.
TRAINING THE NEW HUNTERS
In the real world, Ed and Lorraine's daughter, Judy, didn't become a ghost hunter like her parents, but as seen in Annabelle Comes Home, this universe can embellish and retool her story. It could shift to them training her to carry on the family business years down the line. In the real world, Judy's husband, Tony, was mentored by the Warrens and he took on the ghostly museum, as well as their practice, so this arc would feel like a natural direction.
This would match the romance and scares as seen with Judy's parents in the trilogy too. There's even room for the Warrens to train others to form a team, because they would need disciples if there are so many acolytes around like Isla who want to literally raise Hell on Earth. It'd be a nice change of pace for the franchise, and they already have a young paranormal investigator in Drew that can take lead. He's been their unofficial son in these movies, so the torch can be passed organically for hauntings at the Snedeker house, with the Smurl family or the "White Lady" at Union Cemetery.
THE DARK VAULTS
The Warrens' museum has so many dark relics, such as the Valak painting and the Annabelle doll, while Isla's home also had a vault with devilish relics. If either of these ever get broken into or raided, the Warrens can pursue the thieves. It'd be a fresh spin in the form of a supernatural heist story and an overall conspiracy so they'd have to fight tooth and nail to ensure more evil isn't leaked into the world.
More so, it'd teach the Warrens about consequence because they believe they can't destroy these relics and should store them instead. Isla's father, Kastner, admitted he did the same, but out of ego, so it could be that the Warrens prefer to keep trophies out of hubris rather than finding some way to dispose of them. One has to wonder why the church doesn't store the items, so this strategy can further hype up why these relics cannot be destroyed by God's soldiers, no matter what.
Directed by Michael Chaves, The Conjuring: The Devil Made Me Do It stars Patrick Wilson, Vera Farmiga, Ruairi O'Connor, Sarah Catherine Hook and Julian Hilliard. The film is now in theaters and on HBO Max.