Well, they were right. ESO did flop in 2013. Zero copies sold and zero active subscribers. Not easy to flop any harder than that.
2014 is another matter. I predict a huge boost in subscriptions right around April 4th, 2014. Most likely the result of Zenimax releasing a new hat or something that you can get for your characters and everyone will want one.
Although the guy who said it will be a flop if it doesn't blow everyone else away has a point. There will always be people out there who will consider it a failure if it doesn't svck WoW completely dry of subscriptions and force Blizzard into bankruptcy. They're mostly journalists, bloggers and forum trolls though.