Without getting too spoilerific, it seemed clear from the end of Sinister that Pagan deity Bagul (aka Mr Boogie) was being set up to potentially stalk again. Since the film made north of $85m on a $3m budget, it's no great surprise to hear that producer Jason Blum, via his Blumhouse production company, is setting the wheels in motion for Sinister 2.
The first film involves Ethan Hawke as a hack true crime writer, who moves - along with his wife and kids, duh - into a house that was the site of a previous family's gruesome murder. He then discovers a box of 8mm films of other murders stowed in his attic, and finds his ongoing investigation leading into dark territory. The big bad was eventually revealed as the aforementioned Boogie man, who eats the souls of children and can get at you through pictures of himself (whether they be recordings, photos, drawings, or any other type of graven image).
It's unlikely that any of the original cast will be back second time around (although there might be scope for Bagul expert Vincent D'Onofrio to pop up again), but behind the scenes it's looking as if all will be more or less as it was before. The only major shake-up is that Scott Derrickson is unlikely to direct this time, but he will be back to produce and co-write with his previous cohorts Blum and C. Robert Cargill.
This will mark the third franchise underway at Blumhouse, There are no details available yet on Paranormal Activity 5, although it does already have a release date of October 25 this year. Insidious Chapter 2 meanwhile, is shooting as we speak and is due in September. Blum and Derrickson are also working on an adaptation of Stephen King's The Breathing Method.