If I had to answer the question one way or the other, I would say WoW is dying, but still going strong. WoW is slowly getting phased out in favor of League of Legends, which has become the predominant, main video game due to new content being added on a continual basis and an overall incentives structure that rewards playing the game more. People can also buy skins and enjoy a certain level of avatarization with their favorite champions that, while not as customized as the WoW experience, is still fairly imaginative and diverse for people who are into that kind of stuff.
The fact of the matter is, people have developed strong social bonds grinding through difficult content in the earlier days of WoW, and those bonds typically carry on to today. Certainly, the honeymoon period of experiencing an immersive world unlike any other, and the period of truly novel, challenging, and unpredictable PvE or PvP content, have long passed. After a while, people have experienced all there is to experience. WoW runs on a tried and true formula, and each new expansion is just basically a rehash of what the players have all seen before, just with new skins and a new storyline. The core of the game has remained the same for quite some time now.
But people remain because WoW is one of the only, truly social games out there. It boasts an incredible community, and some people enjoy the various aspects that the game has to offer: Collecting, theory crafting, PvPing, role playing, etc. While yes, I do think that League of Legends has taken over, very few games match exactly what WoW has to offer, namely, an already established social network that's hard to break.More questions on World of Warcraft: