Even alpha testers need to go home for the holidays to be with their families. So with that said, Blizzard is preparing to temporarily pull the plug on the World of Warcraft Legion alpha next week.
The Legion alpha test has seen a limited number of testers invited into the game to try out the game's new features. That includes the new Demon Hunter class and the new legendary weapons. There have been no non-disclosure agreement restrictions placed on any of the content, meaning Twitch and YouTube have seen a rapid stream of Legion-related content. With the main purpose of the alpha to help flesh out bugs and other issues, it means Blizzard staff has been diligently keeping an eye on the alpha to fix issues as they arise. The holiday break means they'll simply be recharging their batteries.
The Legion alpha will go offline on December 21, but Blizzard is pledging to it back in the early part of the new year. An official return date is forthcoming, but in the meantime, find the full hiatus message on Battle.net.