World of Warcraft Shrugs Off Competition

Despite the recent release of a few more high profile MMORPGs, Gamasutra is reporting that World of Warcraft's subscription numbers have now surpassed the 13 million mark.
WoW has actually increased its audience size to 13.1 million unique users as of August. It's like that Star Trek creature, the one that got bigger every time they fired a phaser at it?

I'm infrequently suprised these days, and not because I'm some Nostradamus, I just have good data backing me up and I keep the trends close at hand. But even I thought that with the increased competition and decreased discrectionary income that WoW might be tapering a bit - I mean, the next expansion is a ways off yet so shouldn't we at least be seeing some MMO hiatusing? (yes, not a word or term but it is now and its mine, deal with it. ;) )

It begs the question; if decreased consumer confidence and spending, copious quantities of new competion (some of which is free) and aging content can't slow the Irvine based juggernaut, can anything?