The fact that Legion is gaining popularity instead of losing it?
If you don't know what I'm talking about, here: http://www.icy-veins.com/forums/topi...n-its-history/
"In more detailed statistical news, the overall number is up 25% quarter-over-quarter and 50% year-over-year, with Legion growing WoW's monthly active user numbers by 30% quarter-over-quarter."
Reminder that the numbers for Q2 were released on August 4, roughly when everyone already preordered Legion and their numbers were "tracking in-line with the previous expansion" meaning they had about 10 million at the time. Now, that means Legion's popularity is around the same as Wrath's popularity.
This is huge. By the end of the expansion, Legion might be the best one to date.