So far there has been much speculation about the likely time exclusivity on PS4, but without any explicit confirmation. Today, however, comes an official update from Square Enix, which has updated the cover of the game (bottom) adding the indication "Time Exclusive until 3/3/21".

The title will arrive on Sony consoles on 3/3/2020, so that means it will have a full year of exclusivity and then arrive on the other platforms as well. It's very likely, so from March 2021 we will be able to play it on Xbox as well, perhaps a further improved and enhanced reversal for Project Scarlett. That's great news!