Starfield is Bethesda, so it's going to be a buggy mess that barely works on release and will still have major game breaking bugs ten years later. But it'll have a ton of mods to fix those bugs so the devs don't have to. Might take a while though.
However, I don't think it will dethrone skyrim when it comes to the sheer modding capabilities. I think the only game that could potentially dethrone that is es6.
Personally, I have little interest in starfield. It feels like a scifi game without the scifi if that makes any sense. Everything in the trailer was humans, why does elder scrolls have more interesting races and options? Starfield is a game where you can go to multiple planets and yet... everything is just earth and futuristic utopia. It feels like it lacks creativity.