Online reports are indicating that, yes, all of the cast for NBC's Community will be returning for its fourth season. Chevy Chase's return was in doubt after his much-noted blow-up with Dan Harmon, but apparently he is included on the list of cast members returning for the fall. While Harmon will not be the show runner next season, some sense of continuity will be retained in the cast.
It looks like Nathan Fillion might be playing a superhero afterall. After being considered for roles in Green Lantern, and Captain America,Fillion (most remembered as Malcolm Reynolds in the cult-hit Firefly) is reportedly in final negotiations to play Dr. Hank Pym in the new Avengers film. It hasn't been stated whether Pym would be Ant-man in the film, or just a S.H.I.E.L.D. scientist, but we're holding out hope.