Yes, by making NEW THINGS. NO company continues to sell the same product with new paitings for 100 years. And this is what WoW is. The SAME thing with new colors every expansion. The SAME game since 2004. New stories, talents, raids, dungeons, quests, arenas, etc. don't change the core of the game. Even housing or something would not change anything. It's just another thing to do while doing the same stuff as 2004. THAT is the "problem". This is why a game gets old. This is not fixable by any amount of new content. This is only fixable by a completely new core gameplay. A completely new game!
Oh, and when you now tell me that I don't know... cars are the same since 100 yers and still people buy them I will break your face.