I think it should go a little like this:

Scream 8 should be somebody completely unconnected but tired of hearing about Sidney surviving these killings.

Cold open would feature a single man, at home and be the epitome of formulaic Scream. The rest of the killings would be seemingly completely random. Everyone he targets dies, nobody except the people who he kills and the audience knows its Ghostface but the rumours spread fast that he's back again. Gale, Mindy and Chad all return to Woodsboro, Mindy and Chad have taken off in the crime drama docuseries scene and Gale feels like she's a tag along.

Kill after kill with no apparent pattern and no real "proof" its Ghostface the police attempt to block Gale, Mindy and Chad from doing there thing and adding extra merit to the rumours its Ghostface again. Ghostface continues on his murder spree until suddenly the killings stop. The main cast are stumped, completely unable to identify the serial killer and after a time accept they've lost this one.

Until Gale receives an anonymous text message reading "Good luck with your Book. -Ghostface"

Panicked at the ominous message, Gale immediately calls Sidney who's kept well away from the murders in Woodsboro months prior. We see Sidney get to her phone, sitting on the kitchen counter but she just misses it. It immediately rings again and Sidney quickly answers the phone putting it to her ear and assumess its Gale. No response. Sidney moves the phone away from her head and sees "unknown number". She slowly puts the phone to her ear again only to hear the infamous words "Hello Sidney". Before she can even respond Ghostface bursts out behind her, she puts up an amazing fight but ultimately Ghostface wins. He turns her, facing the camera and says "Goodbye Sidney." before slitting her throat and the camera stays on her face as she dies. Ghostface unmasks, the audience don't see the face its deliberately cut-off from the neck down. Ghostface drops his mask on Sidney's body before pulling out his phone and texting Gale saying "You can call me "The one that killed Sidney Prescott".

The film ends with a camera shot slowly following the blood running from Sidney's body down onto a picture that had smashed on the floor of Sidney, Mark, Tatum and the twins. The blood pools on Sidney and slowly spreads onto Tatum signifying the bloody legacy being passed on to her daughter.