Saw had a complicated mythology. PA started off with bare bones backstory and has slowly been building one (though not one as tightly woven as Saw's was, since it deals with far fewer characters), but I think they made things a bit convoluted this time around without explaining enough. Spoiler (such as which child is really Hunter or if Hunter is just a common possessing spirit, and if so, where'd the other kid come from and how'd Katie lose him? If Toby is possessing Katie, how could he be in the house also?) Sequels do tend to go down in quality (Saw 5 was the low point for that franchise, though I felt 6 recovered nicely and 7 went a bit sideways). I think in the case of PA4, they just didn't innovate enough this time around and played it safe. There was nothing as innovative or world-building in 4 as the oscillating fan and coven backstory in 3. They need to shake things up a bit for the next film and either find a new direction to take events or start building towards a conclusion. I think the obvious choice would be to focus a film on the person (or persons) actually reviewing the found footage from these families and connecting the dots- perhaps even using what they've learned from these videos to combat/confront the witches/demons (ie: observation attracts/empowers Toby, IR lights can detect Toby, physical objects like doors can obstruct Toby- so it is possible to contain Toby, and crosses seem to repel or cause those he possesses pain- so it's possible to harm Toby). Take a sort of Dream Warriors approach so far as turning the tables go, and make it feel like the experiences of the prior films were about something more than just audience scares.