Best Buy Canada has already listed Diablo 3 for the Xbox One on its website by mistake (with the listing being taken down) and now UK website Argos has a listing up for the game too. Just like the Best Buy CA page it shows the Xbox One version of the game as being available to pre-order with a release date of some time in 2014.
Blizzard however has been quick to comment on the matter simply saying:
One of our goals is to bring Diablo 3 to as many players as possible, but we don’t have any other platform announcements to share at this time.
To us that means “yes it is coming to the Xbox One, but we aren’t ready to announce it yet.” In the meantime we expect the Argos listing for the game to be taken down until Blizzard is ready to (hopefully) make the official announcement.