Maybe a city on another world in the far flung future could be interesting. Futuristic but familiar tech. No space travel. I'm thinking along the lines of the worlds in Asimov's Foundation. The world building would be a much greater challenge though compared to their previous games and I doubt they would want to go there. I expect to see more present daySomething sci-fI. But more serious and grounded in tone like Red Dead 2.
Yeah I was going to say 19th century cosmic or gothic horror could be really awesome. Plenty of places in the US or UK or maybe central/eastern Europe for a more fresh setting.
This could be great too. Alan Wake was amazing, but the original idea of an open world was definitely something that I wish we got to see.I'd like their take on a small town. Focus all the design on making a single small town feel like a real place - with a murder mystery or something.
Rockstar's Twin Peaks