> Subscription figures have fallen from 12 million just after the release of the last expansion to 10.2 million

That's probably a cycle that follows every expansion: all of the old players come back, play it, get bored again and leave. I'm not sure this is evidence that it's "fading"

But they've already announced their next game, Diablo III, and they tend to only have a few games in their peak at a time anyway, so we know what they're doing next because they've told us.