What I'd be interested in seeing is before and after stats about play time. In other words, how much those people played BEFORE Lich King was released and now - having hit 80 - how many are still playing and how active they are.

I always feel WoW is a mainstay for many people, something they come back to and play but lose interest in and leave until something comes along, at which point they play it to death then stop again...

It would be interesting to see if that were true...