According to the last last episode (6x02) is Red John all of the six remaining suspects (especially the scene after Jane left Bertrams office with two other suspects and their following conversation). I've read somewhere, that Bruno Heller said it'll be the big disappointment after they reveal the Red John. So, it would be a big disappointment not to have only one real Red John. And in addition the notes of Janes shrink fits to all six of them, the last scene was pretty clear. So there only something like Red John team.