I saw the movie last night and was impressed. If for nothing else than it gives the necessary backstory of the demon(Tobey) connection to the family. It also raises the question(unless I missed it) of what happened to the girls biological dad? I have my suspicions seeing as how things went in this movie.
The next movie has to move forward, a direct sequel to pt.2, cause there is no more viable recording one could do going any further back in time. I feel you almost have to bring in a third party, cops?, in a type of filming the search for Katie(possessed) with Hunter.