Assuming that Jeff Winger and the rest of his study group are on a four year plan at Greendale Community College (which is already two years longer than most people), they'll have a chance to graduate next year as Community has been renewed for a fourth season of 13 episodes. This comes after two days of nail-biting suspense as NBC has been dribbling out their renewal announcements in the slowest possible manner.
Unless the fourth season does some spectacular numbers I would say this is the end of the road for the show; that NBC even gave the perennially underwatched program another year is impressive and kind of nice of them. 13 episodes seems long enough to me; American sitcoms suffer from having to pump out 20-24 episodes a year, and a 13 episode order should allow Dan Harmon and his team to just get to the really good stuff.
But who knows - maybe four seasons is the charm. Or maybe Sony Pictures Television will sell the show to TBS after next season, which is what happened to Cougartown this week. Personally, I think I could be okay with being left wanting more Community than having had too much Community.