There was a leak of bethesdas release schedule during the court hearings, which if you offset the dates due to covid, (starfield was originally taped for 2021) by 2 years, TES6 should be 2026 as the original target was 2024. That would put it as a late Xbox Series life release.
I think I remember reading in an article around then from some Bethesda insider saying they had only just started working on it, despite the first teaser trailer coming out in E3 2018 or w/e. So that timeline actually would make sense