Diablo III community manager, Brandy ‘Nevalistis’ Camel, has said that the upcoming patch 2.4.0 will release simultaneously on PlayStation 4, Xbox One and PC before January 15. In response to a post on Battle.net, Camel said:
The January 15th date is the start of the new season. We plan to release the patch prior to the start of Season 5.
While we typically patch on Tuesdays, dates can always shift if we run into technical issues during deployment preparations. This is why we do not provide hard release dates for any patch.
The patch brings with it Greyhollow island, set item revisions, special dungeons and challenges, empowered rifts, and more. For a comprehensive list of patch notes, head over here.