Minor nitpick: Most of WoW's lost "subscriptions" were actually the active accounts of players in Asia (mainly China) who because of trade laws actually operate under a completely different payment system (buying game time in minute/hour/day increments at varying prices). If a Chinese player purchased a day of WoW, he would technically be a part of that large "twelve million subs".
Blizzard was rather deceptive with that statistic, but the losses incurred by losing so many "subscribers" are equally deceptive. Subscription levels remain largely steady within NA and EU regions, where most of WoW's income comes from.