I do not know who Red John is, but I have a few things to say. 

1) The writers would be insulting the viewers' intelligence by revealing PJ as RJ. 

2) That Susan Darcy lady must have a skeleton in her closet!

3) At the end of the most recent episode, (5 x 03) did something not seem off to you when Lisbon goes to play poker with FBI and finds her boss, CBI director (Bertram) there too??! That scene has a weird vibe to it and I can see RJ having something to do with that gathering. Remember, RJ has a friend in the FBI. But I can't say for sure that Bertram is our guy because he seems taller than the guy in the mask in season 2 finale and because I don't see a director like that doing the dirty job by himself.