Since hogging the sheets and dragging people across the floor can only get you through so many sequels, the Paranormal Activity series has to find new gimmicks. Kind of like videogames in a post-Wii world. Hence, the Kinect’s appearance in Paranormal Activity 4. According to the teenage monster fodder in the trailer:
You guys want to see something really cool with the Kinect that you can do? Kinect projects tracking dots.
Note that the trailer for last year’s Paranormal Activity 3 had all sorts of devious misdirection for including scenes that didn’t appear in the actual movie. So for all we know, the demon in Paranormal Activity 4 might be more of a Wii U or Playstation Move kind of demon.