All of World of Warcraft’s old content will only require a subscription to be played according to the Blizzard store. You will receive everything that is part of the game -except for the new Battle for Azeroth expansion- when you purchase a monthly subscription. Before this change, you had to buy the base game and all expansion in the form of The Battle Chest but this item is no longer available on the Blizzard store. As of writing, Blizzard has yet to come out with a statement on the change but we expect it to be permanent.
Not having to purchase The Battle Chest lowers the barrier of entry significantly. People who have yet to try out World of Warcraft can now more easily do so by just purchasing a one-month subscription and then can check out the entire game by themselves. It also makes the purchasing process a lot more clear. Many people were probably put off that they had to make a big investment to buy the Battle Chest and then still had to purchase a subscription. Players that want to play the new Battle for Azeroth expansion will still need to purchase that expansion for the one-time fee of $49.99.
The change will probably help new players with finding their way to the game. Although the game is far from dying off, it’s definitely not as big of a phenomenon as it used to be. Attracting new players to the game is a great way to bring World of Warcraft back in the spotlight and increase their player base to include more players than only the hard-core fans and players that return every expansion or so. It will also help with the survivability of the game as a whole bunch of new players in the game will probably drive up their profits more than players buying the Battle Chest every so often.