I think this statement by Heller narrows things down a bit: "The Red John story is going to be moving at a very fast pace with no vamping, no tricks. Well, there'll be tricks, but we won't be fooling the audience or messing with them," Heller said.   

I believe that means no “Lorelei is alive”, no “it’s Michael Kirkland, the missing twin” no “it’s John Johnson” the guy we saw only that once and definitely no “it’s Van Pelt because she has red hair and likes to have sex all the time”, lol.

It doesn’t necessarily preclude Partridge faking his own death, I still figure that as a possibility since dedicated fans wouldn’t be fooled, as evidenced by the number of Partridge theories on this site, but most of the other more creative theories are out the window IMO.

Personally, I still believe Partridge is dead and it’s Haffner or Bertram for various reasons that have been talked about ad naseum .