Red John is not a person. Cult or organization. Red John's Smiley Face is signature , Tyger Tyger is password of this community. 

if its true rigsby and GVP wont be around for long, i think rigsby will be killed by someone from tyger tyger for looking into kirklands death.

GVP will be devasted and RJ will use the opportunity to use her as a tool against TT without revealing himself to her (Heller giving everyone their wish that GVP is somehow bad). GVP would help RJ since TT killed her husband although shes unwilling to work for RJ. She somehows figure one important clue which will determine RJ though and she proceeds to tell PJ everything, leading RJ to kill her. PJ finally figures who is RJ though with GVP's info, and still get to know about TT. However, TT also figures out who RJ is and kills him before PJ gets to him. This causes PJ to not get his revenge and since TT is a bad organization, PJ decides to bring them down. This serves as a story continuation after RJ dies. 

Damn, i should be the writer for the show instead of Heller.

To tell the truth, it's a little bit strange that now when RJ knows that Jane is getting closer to him he goes and commits a murder in such an unorganised way. I guess RJ is smart enough not to demonstrate something that can easily give him away (like this tattoo).I don't quite understand why Patrick decided  that the detective had been killed by RJ ? RJ definitely knew that the detective was being spied on and it was extremely risky for him to murder her on his own.
Another strange thing is that it seemed she knew Red John (considering the way she greeted him). Then why would she describe his tattoo?
As far as I'm concerned, that wasn't RJ's kind of work. Probably I'm missing something that made PJ sure about the murderer.
BTW, after this episode I'm prone to believe that Haffner is not RJ. What he told Lisbon sounded more like he was one of RJ's puppets.

Your mom is Red John.

thy patridge shall rise again.

however below there is a theory "not fun at all" but interesting about Partridge being RJ and being killed by tiger.org and that will keep PJ wondering why and seeking revenge.

and it will reconcile partidge fans and none fans.

This probably isn't what will happen, but I thought it was a fun theory:

What if Brett Partridge WAS Red John, and the Tyger Tyger group killed him before Patrick could get to him?

This would lead to more seasons of "The Mentalist" because then Patrick could shift his focus from Red John, to taking down the secret organization in law enforcement that denied him of his revenge against RJ.

It's a long shot, but I thought it was a fun theory

some people here have watched DEXTER too much,,

in the mentalist there is no such thing as forensic serial killer guys, please.

Partridge is dead guys dead and buried.

you think we'll have resurrection on Christmas??