WoW peaked with something like 12 million subs during the Wrath of the Lich King expansion, and rightfully so, it was quite possibly the greatest MMO expansion ever developed, the greatest expansion for any game type period.
Since that expansion the sub numbers have bounced around from 8-10 million subs when a new xpack launches to 4-5 million by the end of the expansions life. at at average of 15 bucks a month per sub, WoW is still a cash cow even at its lowest levels. I open face laugh with my fists pushing in my sides when people say WoW is dying. Rift is dying. Star Wars The Old Republic is on life support. WoW still has, and I'm a betting man, I would say at least 10 more years.
Funny story.
I went to Gamestop today to get me Cuphead and Mugman plushy's for my son and when I was checking out, the guy behind the counter was asking people if they wanted presales of upcoming games for all systems. When it got to me, I mentioned I'm usually a PC guy and he said that the new WoW expansion just went to presale and the only way I would get a copy day one is if I preorder, I said I already did it digitally through Blizzard. He looked at me like he was going to cry and passed me off to another associate. The only thing I could think of, "Was it something I said?".