This is the point that bothers me the most - total waste of time. Of course Scream was never generic because of its satirical nature, but a 4th film, years later, with new people, really would be, and it just makes a joke of it. It's BOUND to have some vague connection to the past, but it's hardly worth it.
Scream 3 was f*cked up massively, but that ship has sailed now, may as well leave it be. Even if the 4th is amazing it won't change what's gone before.
If they got Neve, Courtney and David back for proper roles, maybe. A good script, budget etc. Basically if it was as perfect as could be expected...but there's still little point. And it won't truly feel like part of the series, much like the 4th Indiana film. Like a vanity project or something.