the daughter should be the opening kill

Think about it, it'd be like people being surprised by Drew Barrymore dying in the original's opening all over again. Because here we all are, assuming she'll be a central protagonist. And, that'll probably be the case. They like to act like there are no character shields, but there are, kind of like we knew Arya wouldn't randomly get killed off by the Waif in Game of Thrones. But imagine, the opening of 7 could be like a redo of the opening of the original, with their daughter as the victim, and Sidney and Mark coming home and finding her like Casey's parents did. It would definitely set things in motion. And Sidney, even when she's pro-active so as to be less of a victim, she's still usually playing defense. But this would give her reason to get bent for vengeance and seek out Ghost Face.

But, likelier the opening kill will be a friend or classmate of the daughter's, to set it up. Still wouldn't be surprised if it's intentionally similar to Casey's death though. I doubt it'll be set in Woodsboro, I think Sidney wants to be away from there, but I think the killer will of course still try to emulate Woodsboro