Blizzard President, Mike Ybarra, has put an end to the speculation, stating that Diablo 4 will not be launching on Game Pass. The rumor started when a banner featuring the game on a Brazilian payment app suggested it could be played through Xbox Game Pass. However, Ybarra confirmed that this is not happening.
While this latest announcement confirms that Diablo 4 will not be joining Game Pass anytime soon, it does not rule out the possibility in the future. If Microsoft's acquisition of Activision Blizzard goes through, it is possible that a range of Blizzard games, including the first three Diablo games, could become available on the service.