This is not about who Red John is i dont have an idea anymore, is just about 2 clues i found
watching the episode of tonight, here we go. 

1.- In the description of red john in the final seconds of the chapter, " hes an excelent whisteler" ( i dont know if its spelled like that im mexican) and in that cutscene we see Sheriff Mccalister whistling, and when Ray Haffner visits Lisbon at the hospital, he leaves the room whistling.

2.- Im asuming all of you have noticed that ( probably this is just heller being a troll ) they have tried to shove Ron on our faces the last 2 episodes? Even on the preview of the episode 3, the only thing even remotely related to Red John on the Preview is that we see Ron one more time, 3 episodes in a Row.

So this is my 2 cents about todays episode, i dont think is Ron i just used his picture, but they are going the extra mile to shove him on our faces.