So we might have a release date for Diablo III's Reaper of Souls expansion, courtesy Blizzard's Russian forums. Redditor skyline185 posted a screencap from the forums with a blue post giving the date 25/03/14. Of course, this isn't official and no doubt the author will be facing a slap on the wrist.
Coincidentally, as someone else on Reddit noted, this is the same date that Gamespot has for the Reaper of Souls strategy guide. Or maybe it's not a coincidence at all.