I am absolutely gutted by that news story.
If they can't get Neve to play Sidney, then don't make the movie.
I won't be seeing it if Sidney is to die in it, what is the point exactly?
I was dubious of a Scream 4 from the start, it's unneccessary, I love the trilogy as it is, why add to it when it really isn't needed. I would have seen it if it was to be a sort of reboot, copycat killer but with totally different victims, but to bring back Dewey and Gale but have Sidney dead is just an absolute insult!