They don't care because they know the game is 10 years old and has had it's run. To be honest, the legion expansion announcement surprised me. That may mean that Blizzard doesn't have another title close enough to keep fans happy. Certainly they lost "Titan" to Bungie and it sounded like they were banking on that.
Square isn't doing what blizzard does with their cash shop and the game is a new title, not one on the way out. .