Just seen this on MMO champion, originally it came from a Chinese English langauge site

It appears legitimate here, the 18 month gaps between WoW expansions make sense (they originally wanted to release an expac a year, but I think that was before updates started adding real content), so far though they have slipped by at least 3 months at least each time. The current one has only 2 patches scheduled for it, if they follow form then these will be released in 6 months time and then another 3-6 months after it.
Giving the lack of high level content, 8 dungeons and 3 raids I believe, since even average players like me can complete the games raiding outside of hardmode in a month (hardmode needs a serious commited guild) player numbers have dwindled progressively faster after each patch in WotLK. To me it seems the easier they make it to progress (its possible to get a full set of top level raid gear in a few days right now) the faster the progression gets consumed and the quicker people get bored. Couple that to the focus on the newbie experience where most of the new content is on Cata I'm predicting March onwards will be quiet for WoW with a pick up for 1-2 months after each patch.
The social pressure to play with it being so more likely that a friend already is playing is enough, but the Blizzard hype machine though is incredible.
For example if any other company tried to release a game like Starcraft II they'd have been about 10 years late to the market and it would have been a disaster. C&C V1 gameplay (without the cool music and Kane) but adding in animated cut scenes brought nothing new to the genre, nor added any polish to the formulae already there (at least to me, I experienced it on a friends "free to play" copy here :P). But fire enough tv adverts up, play the games community press like a two bit fiddle and people were talking about it all across the web and lashing out £40 to get their hands on it.
Right now I'm even feeling the urge to buy Cata, its for the playing with friends bit, but since its a £40 payment to do so I'm really not keen, but if I don't then the option to pay a month to join up with them goes.
Anyway, if I was Smedley and looking to launch EQ2 expansions (or any other game) at the optimum time I'd be looking at these dates with a lot of interest, with Blizzards past history a 3 month delay is almost expected. Based on that I wonder if Smedley already has this data on his desk, Velious hits at a perfect downtime for WoW (even if it slipped 2 months) and if further releases keep to the 1 year rough schedule they hit downtimes perfectly each time.