Good point, but Blizzard might surprise us. Besides their usual posturing and then under-delivering due to perceived laziness and/or limited development resources, allied races (sub-races) and how many we've gotten, and their successful implementation was a surprise to everyone, and while fourth specs are clearly more of a challenge to implement, if they have the time and the desire, it's not inconceivable for Blizzard to pull off. After all, when have they actually implemented any new class without issues and bugs. And introducing them gradually instead of all at once gives them the leg room to find tune each one.