If they did try to do another Community season, my feeling is that they should have it center around an entirely new cast, in a study group in Jeff's class.
That's exactly my point. Get rid of everyone, Jeff can do guest spots as he's probably busy too as the teacher. The only character that transfers over is the Dean and then we have 5-7 new people, and some minor characters in the background.
Making Dean the main character would never work, but having him around keeps the shows connected.