"All data is gathered from Battle.net API usign auction house data and guild rosters."
aka there is inaccuracy abound, mostly in missing data. Not in a guild? Not counted.
You forget to account for TW, KR, and CN servers, 6.795+M on just EU/US + CN/TW/KR(which have just as large a playerbase but don't use the same sites as EU/US because of language barrier.
Stop doomsaying, Live WoW is fine, yeah Vanilla is great and I wanna see Legacy server but Jesus H Christ you fear monger on this forum like WW3 is about to start.