In an interview with VideoGamer.com, Dave Kosak, the lead quest designer for World of Warcraft, stated that patch 4.3 would be the last major update in relation to Cataclysm before the Mists of Pandaria expansion.
4.3 is definitely the climax of Cataclysm so there’s no more Cataclysm content. Traditionally we’ve had a grace period where we patch the game before the expansion comes out and you get sort of mechanical changes before you get the new expansion content. So we’ll have a world event prior to Mists of Pandaria, but that’s mostly a part of Mists of Pandaria’s launch and it’s not really more Cataclysm content.
It seems the release of Mists of Pandaria is closer then we thought, much closer. Looking at the time-span between each expansion’s release date, we can see that on average it’s slightly less than 2 years.
Burning Crusade > Wrath of the Lich King – 22 months
Wrath of the Lich King > Cataclysm – 25 months
Cataclysm > Mists of Pandaria – 13 months (so far)
With no major patch updates planned, I would doubt Blizzard would wait another 9-10 months for the release of Mist of Pandaria. So does this mean we’ll see a summer release? Perhaps, perhaps not. Blizzard is also known to make gamers wait, so a Nov or Dec release is just as likely.