Another Blizzcon is in the books, and the majority of my self-described "incorrect Blizzcon predictions" for the year were proven wrong before the convention even opened. I suppose you can split hairs on whether the event is "widely viewed as a disappointment" for lack of an announcement concerning the Mystery Fourth Project, but what Blizzard did NOT announce was almost as interesting as what they did.
Diablo III's beta was mentioned (some attendees will win keys), but the SCII expansion/sequel's beta was not, and the game apparently is not expected in 2011. Also not expected in 2011 is even the ANNOUNCEMENT of the Mystery Fourth Project, which Blizz says won't be revealed until 2012. (This is remarkable since game itself will probably still be 1-3 years out AFTER the announcement; relatively few games have the luxury of a dev cycle this long.) These announcements mean that Blizzard apparently intends for WoW to continue to be the company's flagship MMO quite possibly up to the game's tenth birthday in 2014.
In that context, it's interesting to see how little we got out of Blizzcon about the content patches of the Cataclysm era. At Blizzcon 2008, just prior to the release of Wrath, Blizzard held a community summit that outlined the planned content patches of 2009. The actual convention itself included tidbits about patch 3.1 (described at the con as almost complete), such as dual specs and swimming ground mounts. At this year's event, we got some pictures of new dungeons for patch 4.1 and a comment from Tom Chilton that Deathwing will arrive in either patch 4.2 or 4.3.
Why Blizzard is considering only two content patches for the Cataclysm era?
Are they thinking that Cataclysm sets a precedent of five levels per expansion that would allow them to complete a less ambitious fifth expansion sooner than late 2012? Blizzard has been saying that they wanted annual expansions for years now, but previously have never delivered. Perhaps the added pressure of having the followup so far out is pushing them to pick up the pace? Perhaps Bobby Kotick is demanding more box sales? Or perhaps this is Blizz-ness as usual, and we'll see 4.1 in April 2011, 4.2 (sans Deathwing) in October 2011 along with a Blizzcon announcement of the fifth expansion, 4.3 in March 2012 and the new expansion in November/December 2012.
Given my track record, I'd hesitate to guess. Given Blizzard's track record, though, the latter may be the most likely.