If you get 10 random people in a room and blindly played a clip of Scarlett Johansson speaking normally (ie not lines from a movie), I'd put money that exactly zero out of 10 people could identify the speaker. It's one thing to copyright a performance or own a likeness. Owning the sound of a voice is scary territory we do not want to get into, or the estate of every singer will be suing the estate of every other sing…
If you had picked someone with a less disctinct voice you may have a point, but ScarJo's voice is very distinct. I'd bet on 10/10 people who are engaged in pop culture and 5/10 general people guessing correctly.
I think though that Sky's performance is similar to ScarJo's performance in Her. They're both playing AI voices.