Speaking with Windows Central, a representative of Blizzard noted that the studio has been impressed with the new Xbox One X console, and it plans to utilise all that extra power in an upcoming Overwatch update. Dialblo III, which runs at a silky smooth 60fps in 4K already on the console, points to something special coming to Overwatch fans on Xbox.
The statement notes that the "Overwatch team is excited with great possibilities Xbox One X opens. The team is currently exploring how the game experience can be enhanced on this platform to leverage the console's incredible hardware, and is working on implementing 4K resolution in the game on Xbox One X". Also going on to say that work will need to be done on the UI to support the new resolution and we will be getting full details on the upcoming update at a later date.