The Twin Theory
How cool would it have been to reveal that Normam is actually a twin in this film. Each film had their own twist: 1. Norman turned out to be the killer in the first film. 2: The killer ended up being Norman's real mom in the second film. 3: And maybe the killer was or maybe it would have been revealed that Norman was a twin in this film.
Would have been cool since his film was really the less of the original trilogy.