I think the best ending would be if Patrick Jane himself would be Red John. His other personality (which is RJ) purposely gives him hints for people that could be Red John so Patrick Jane goes and kills them (Sheriff, Timothy). Slowly Patrick Jane will become a serial Killer and will someday discover his true self and his other personality. He realizes that he is a danger for Lisbon and his friends and decides to kill himself to find true peace.
How do you find this theory?
plausible
unlikely