What they SHOULD have done
Scream 4 left off on such a bad note and the worst movie in the franchise to me, this should have been a closure movie. Instead of having this be the start of a new string of movies, which has gotten so ridiculous at this point, they should have used this to end everything and tie up all those ends with returning characters with Sidney, Gale, Dewey, and then survivors like Joel, Hank Loomis, Mark, Martha, etc. and done good with that angle.
I always felt like Scream 3 missed the ball not having Hank Loomis be the killer and the director of Stab 3 because introducing a brother made no sense given how little time we got to invest in that whole dynamic. Hank is a familiar character and having an established history with Sidney's mother, and given what occurred with his whole family, it makes sense he would have it out for Sidney despite being the cause for the affair, but killers don't think straight when they lose the ones they love. Him being the killer this time around I would have made a given.