Link here: http://www.deadline.com/2012/11/chevy-chase-leaving-nbcs-community/

This is pretty much the final season then. The good news is that most of the episodes for Season 4 have already been filmed; he just won't appear in the one or two that haven't. The bad news is there seems to be only 13 episodes now without the possibility of a back nine. Here's hoping they can find a convincing way to write out his character (assuming he gave them enough time to do that; can't tell at this point).