I think that it is very plausible that red john is an identity made up by the
TT organization for whatever reason that will be revealed. All the top members are part of the character of red john. For instance bret stiles is the one that seduces/hypnotizes red john followers and maybe one person does the actual killing or they take turns. I just don't see any other way for the red john reveal to be surprising or interesting.  unless the make jane red john which is my secret wish because it would be such an awesome twist.