6th and 7th expansions are being planned for World of Warcraft
In a recent interview with Korean mmo reporter, PlayersCutTV, World of Warcraft's Senior Game Designer, Brian Holinka reassured players that this was not the case.
"We've said we want to quicken the pace of the expansions, and that's certainly something that we've changed the entire structure of the team to do. I can tell you for a fact that we've already began work on formulating the plan of the next expansion...and the one after that, so we very much have a big plan here of keeping content coming."
Although the gaps between expansions were initially quite big, the gap between the forth expansion, Mists of Pandaria and the upcoming Warlords of Draenor is only two years, meaning that Blizzard can at least see another 4 or so years in the mmo, which is already sitting at the 10 years old mark. The spikes in interest whenever a World of Warcraft expansion launches certainly warrant an increase in expansion development, and as the mmo gets older and the risk of players wandering to other games rises.
"I can't see WoW being gone five years from now; I feel like people who love it are still going to be playing it and we're still going to be making content for people as long as they want to play it."