Most people considered World of Warcraft's recent turn around of falling subscriber numbers as only due to the new content introduced in Worlords of Draenor; something that most people were expected to blow through in a few weeks and then drop the game once again. However either it's sustaining people much longer than expected, or the game has gotten a lot better in the eyes of many, as several months on from release and the subscriber numbers have broken through the 10 million barrier once again, taking the game to its highest number of paying customers in the past two years.
Of course this is still quite a long way from its peak of near 13 million subscribers back when Cataclysm was released, but it's a damn sight better than the less than seven million it was not too long ago. Worlords of Draenor has really given the decade old game a shot of adrenaline.
WoW has been a bit of an anomaly for a long time of course, being the only real subscriber MMO that's succeeding on a massive level and that's been the case for many years. While most other MMOs have needed to go the free to play route in order to remain profitable, using micro-transactions for aesthetics and experience boosts to make their money, Blizzard's giant MMO just keeps chugging along.
You have to wonder how long it can last, but with over 10 million still playing, it seems unlikely to halt its progression any time soon. Of course it also seems unlikely that it will ever peak like it once did, but eight digit subscriber numbers is still very impressive.