According to this article Donald Glover will only be in 5 of 13 episodes in Season Five.

Whether or not Community is as good now as when it started is a topic that could be easily debated (I fall on the side of not, it's gotten too weird for me most of the time). But, I don't think it could be debated that the show needs Donald Glover, if only for the simple fact that I really, really like looking at him. Plus I really like his character, he's got some of the most quotable lines and best moments in the series.