It's the last MMO we get currently.
Every single MMO put before us has been completely decimated. Swtor, arguably the most expensive MMO ever made failed horribly, now its just some cheap trash, with each expansion getting lazier and lazier. In rise of the hutt cartel, there were atleast different stories from faction to faction. Now in Shadow of revan everyone gets the same story. TorHead even got shut down because most people considered Swtor a joke by now, and no one updated it so.
Wildstar got destoryed because it was too hardcore, and casuals are the bread and butter of all MMOS.
ESO didn't exactly fail, it going buy to play was planned ( I think .) Skyrim fans bash the game, but they will bash and hate anything so.
Archeage failed horribly because it was full of hackers and gold sellers, innocent people were banned etc. Wonder how a F2P game died.
Then we have the minor MMOS such as Tera, Final fantasy, Eve online, etc. While Eve has managed to keep their subscription, it isnt exactly the most popular MMO on the market.
And then we have Everquest next, the last MMO, that stands. If this fails, WoW will remain supreme over all others. Why is it that all other MMOS have failed? As far as I know, guild wars 2 is the only MMO that has been successful that isnt WoW.