80 dollars for the base edition.
GTA V, Skyrim, Witcher 3, Fallout 4 despise being extremely hyped up at the time still cost the same as any other full price AAA game at the end. So doubt it'll be any different now. GTA VI will most likely still just cost the same as the other full priced games which would be 80. Maybe just maybe I can see them doing 90 but really doubt it'll be 100 or more for the base edition as we're still in 2020s not 2030s yet.
90% sure it'll be 80 dollars for the base game and 10% chance they'll try to up it to 90 which I doubt.