K-ON Manga to End in September
The latest chapter of the K-ON manga in Manga Time Kirara magazine has announced that the next issue, which goes on sale September 9 in Japan, will contain the finale installment of the story. The manga has been running in the magazine since early 2007, meaning it will have a little over three & a half years. Which indeed means the story has essentially taken place in real time, as high school is only three years long in Japan. We knew that the girls were due to graduate & once the main four are out of high school that's pretty much it for the story.
Perhaps not so coincidentally, the second season of the anime is also expected to come to an end this September. Perhaps they're trying to do a simultaneous ending just like FullMetal Alchemist & ToraDora did before it. The ending for season two is expected to be about the girls graduating, after all. Is this really the end of K-ON, or is a spin-off manga in the works? K-ON: the College Years? Or perhaps changing the focus to Azusa, Ui, & Jun as the stars?
Source: http://www.moetron.com/2010/08/06/k-on-manga-ends-in-september