Before last night's episode I was thinking that Kirkland was not Red John, but was working with Red John. I don't recall the specific details, but in season 5 Kirkland killed a man in the hospital who had information regarding Red John, before Jane could question him. Kirkland also interfered with Jane's attempts to question the man when he was placed in an ambulance. At the time I thought he was protecting Red John, but given what was revealed last night, I'm not sure that makes a lot of sense.
Prior to last night's episode my money was on Ray Haffner being Red John partly because he has always been the least likable (to me) of the 7 suspects. The guy just gets under my skin. But since he is in the previews for next week, I'm not so certain now.
The presence of the shadowy group of individuals in California law enforcement has been confirmed; so what relationship does Red John have to that group? Is he a member / founder or is he an adversary? Not really sure. I think the law enforcement group ties in with Bret Stiles and Visualize somehow.
More to think about.