The developers of Age of Empires Online have just made a slightly somber post on the official blog detailing the future of the game, and it's not too bright. Barring one more small patch that will arrive shortly, Age of Empires Online will not be getting any more content at all.
It means that there will be no new content created for AOEO. There is a small amount of content still in the pipeline that will be released in the next few weeks, but that is all. No new features will be added. Most significantly, no new civilizations will be released; the six existing ones are the complete and final set.
The game is not closing but it's still not the best news to year for fans.