A friend of mine told me a Chinese proverb the other day. He said, "A man looked at a mountain that was next to his farm and said, "These mountains are blocking land that we could be using." So he made up his mind to move them. He would take stones from the bottom and move them away into the ocean. An old man happened to be passing by and laughed at him, saying that he would never be able to move the mountain. The man simply smiled at him and said, "Yes, but I have sons who will help. And my son's sons will, as well as their sons. And together we will move the mountain.""
Consider the developers of a game the mountain, and the man and his sons the players. In a successful game the player base will grow larger and larger, and should it hit a cap, better at their job.
What we see happening in World of Warcraft is a unique case in the industry, and one that many games that try and emulate their model should be aware of: endgame content problems. The massive player base of WoW as well as the skill of the players has brought the game to a point where the developers cannot create content fast enough for the players to not get bored before the next tier comes out. It simply does not last as long as it used to.
And personally, I don't believe it should. I do not believe that the endgame raiding model is a good model for a sustainable game. Has it been made into sustainable businesses, yes. I'd be an idiot not to see that. But I think it's a terrible game model. The model says to players from the get-go, "The fun part of the game is at max level. Everything else is just a means to an end.". It encourages developers to keep adding to the top of the game without altering the rest of the world. Which doesn't make it much of a world at all, just a static setting.
More importantly, it makes the only goals for the players the ones set by the developers. Though that may sound odd at first, consider this: In WoW, your options for endgame are PvP, PvE, start a new character or play with the market. The game is so rigidly structured that the developers are in an arms race to create new content before players get bored with the old content. Which then sets the mindset that the old content isn't meant to be fun. That part, I will admit, is a catch-22.
I believe Blizzard and WoW are currently at the tipping point where the players are starting to overtake the developers in terms of consuming content. Being incapable of adding any significant content to anything but the endgame except in very special scenarios is not a great way to sustain a virtual world. It may sustain a game, but a very rigid game. The experience is only extended, not broadened. You don't get to do new things, you only do the same things in different scenarios.
This has been a semi-rant, brought to you by Straw Fellow. Also, I'm not even sure if the story at the beginning was correct in the slightest.