I don’t think so, the MMO-market is just changing and having a creative crisis.
Nowadays there are a lot Free2Play theme-park MMO which have a “high“ quality, and so deduct players from the MMOs based on a monthly fee. Who want to buy something, when he can get it for free? Also the user doesn’t play a game when he is at the highest level. He complains about the lack of content and starts a new MMO. Because there are enough to be played, not only WoW, Ultima Online and Everquest like nine years ago (that’s when WoW were publicized).
The other big problem is that MMOs don’t advance. They are stuck and nearly all are based on the same system like WoW/Everquest. Some games like Tera or Conan tried to change something. But only just a bit. So mastering a game isn’t so difficult for a player because he knows how it works (good to see at the Call of Duty Series: You’ve played one, learned all necessary skill, and every new game you just repeat your learned skills; so you become faster and reach the end more quickly). Even the world is nearly the same: a fantasy world with human, elf, dwarfs, etc. (sometimes they have other names). So the user has no reason to explore the world, because he already knows it.
But this is normal for every product (see Product life-cycle management). Normally it would be time for a relaunch.