TBC announced @ Blizzcon '05 (October 25, 2005) ... released 1/16/07
Span =~15 months
WotLK announced @ Blizzcon '07 (August 2, 2007)
+ 15 months = January 2009
Also, I seem to recall that during the TBC release that Blizz said something about wanting to roll out expansions on a roughly annual basis. That would imply late Summer 08 assuming Bliz hit their own schedules. Hahahahaha.
Either way, sounds like a Christmas '08 target release kinda thing.
I find it hard to believe that Blizz would be reactive to another company, regardless of Warhammer. If their design conceit was huge back in the WCIII days, it's just out of this world now. And from the Vivendi people I've talked to, they are indeed hands-off with respect to Blizz so I don't think they'd get a lot of corporate pressure.
But...
a) Who knows how far along they are with development. Obviously they'd been working TBC well before the official announcement. So the spans above aren't fully meaningful.
b) Who knows how hard the technical side is on new stuff. Seems like they are doing some graphics upgradey type stuff and to presumably that's a bit of a different beast than just drawing up and populating a new zone and programming quests.
I am guessing that Mirakle is just dissappointed that neither "Tote Bag Kitty Lagoon" nor "The Shire" are among the new zones....