I don't really care that much about the latest in WoW subscriber numbers, for the reasons that Tobold and Wilhelm describe. While it is likely that some of the current losses represent a vote of no confidence in the Cataclysm, what happens in the next year will matter a lot more to the future of WoW than what happened in the last year. It will take more than one down expansion to spell the doom of what is likely the world's most lucrative game. Two expansions that are not well received, with 18-24 month dev cycles each, would leave the game in "unsatisfactory" status for 3+ years, which would be far harder to rebound from.
In this context, I'm more interested in a separate tidbit from the call, reported by both Gamasutra and MMO-Champion: 2012 will see a "minimum of two highly-anticipated new titles from Blizzard Entertainment, including Diablo III".
Assuming no one wants to quibble about whether Blizzard titles are "highly-anticipated", most people would probably agree that they expect three Blizzard titles in 2012 - DIII, the first Starcraft II expansion (Heart of the Swarm), and Mists of Pandaria. So, which one of the two expansions could potentially miss 2012?
It's possible that Bobby Kotick is simply being conservative - i.e. that both expansions are equally likely to launch comfortably within 2012, but that saying a "minimum of two" just provides insurance in case an asteroid destroys half of the Blizzard HQ. Given that SCII was out six months earlier than Cataclysm, however, its expansion should be six months closer to completion. The possible implication is that Heart of the Swarm is slated for a Q2 release with no reasonable possibility of being delayed to 2013, while Pandaria is penciled in for a Q3 2012 release - just close enough to the end of the year that Kotick doesn't want to go on the record promising that it won't slip into 2013.
What we saw at Blizzcon seemed to be further along than past expansions at their unveiling, which had me thinking that a mid-late summer release might be on the table. If my new guess is right, the plan is for Blizzard to respond to possibly the most serious threat in the game's life with the same leisurely 20+ month development cycle that they have always taken (and a release date of September or later). This would be much more concerning than plus or minus a few hundred thousand customers to the subscription count.