The information comes from the Blizzard Shop. Blizzard has done away with the old Battle Chest, so access to base WoW and every expansion up to this point is now part of the $14.99 United States dollars monthly subscription.
Instead, all of the previously released Warcraft content is now available for the £9.99 monthly subscription fee.
Since its release way back in 2004, World of Warcraft has stuck to a very familiar revenue model.
"In Battle for Azeroth, the stakes for the Alliance and the Horde are incredibly high, and a player's faction will have a more meaningful impact on their experience than in any World of Warcraft expansion to date", said Mike Morhaime, CEO and cofounder of Blizzard Entertainment.
Prior to this change, players were required to purchase previous expansions through the game's Battle chest, but as of today, this is no longer required.
This is the anti-Guild Wars formula, which charges for the base game and expansions, but lets you play for free after that, or offers free to play options for those who want to get their feet wet before spending any money. You buy the base game, and the expansions, and then the monthly subscription. The one exception to that is future expansion packs including the forthcoming Battle for Azeroth.
By removing the need to buy the game, Blizzard both lowers the barrier to entry and clears up any potential confusion.
The Battle for Azeroth expansion will be available August 14th. With so much content included in the subscription, though, I'm sure many players will now wait to see if this latest expansion eventually gets added for free as part of the subscription rather than buying it next month.