And.. at the end of the day, there were a lot of people who simply didn't like Pandaria and/or pandas. There was unrest at the announcement, unease during the beta cycle, and finally on release, people gave it a chance... but they leveled to 90 and found themselves no happier about it than they had been upon announcement. Within 3 months post-release Pandaria was sinking hard and hasn't recovered. Blizzard has since tried to fix some of the problems they created in 5.0 (the terribad rep/daily grind, for example). But it was too late, a lot of people had already given up and moved on. A lot of people still look on Pandaria with a jaundiced eye and won't come back for a content patch, but perhaps can be lured back by a whole new 6.0 expansion that promises to reset things a bit.
This Blizzcon will be fascinating. A lot has changed since the last one. The last time we had a Blizzcon, the game had suffered some sub loss, but nothing like what has happened since then. And although the most hardcore of hardcore fanboys and girls attend Blizzcon and hence the local audience will be rapt and adoring, they have to be aware that every single word they say will be reproduced for the masses, and will either cement peoples' determination to stay away, or convince them to give WoW another shot.