I never bought into the #sixseasonsandamovie stuff, I just wanted four seasons with a satisfying finale where the characters graduated. But due to season 4 being cut short and ending with only Jeff and Pierce graduating, a fifth season with the other five characters graduating makes sense. After that, I think a sixth season about their lives after college would be a fitting tribute to the fan-base that kept the show alive. Then a direct-to-DVD movie.
Season 4 was definitely the weakest season so far. I had assumed that the season would grow out of its awkward phase after a few episodes as the new showrunners got into their own groove, but it didn't really happen outside of a few notable episodes. It tried too hard to attach itself to Harmon's Community with constant references to previous seasons, but it just couldn't live up to the style it was trying to emulate. Hopefully the feedback from this season will help them set a better course next season, especially now that the dead wood that is Pierce is gone.