First off, even though this is a theory that accuses Patrick Jane of being Red John it is more than obvious that at the end of the show someone else will be revealed as the serial killer. Jane being John would be far too classy for the general audience that seems to prefer rather cliched character constellations.

Regarding all those comments that don't get tired of pointing out that this and that episode supposedly makes it impossible for Jane to be John I'd like to say that there is one episode that invalidates all impossibility claims regardless of what came before or thereafter: The episode in which Jane killed Red John only to learn that the man he had killed wasn't Red John.

"How can John talk to Jane if Jane himself is John? How can John touch Jane if Jane himself is John?"

Answer: The Red John who touched and talked to Jane wasn't Red John. Just as the Red John who was killed by Jane wasn't Red John. That means every person presented to the audience as Red John is possibly not Red John. The man who was killed by Jane wasn't just an imposter who tried to be Red John on the weekends or some henchman trying to cover his boss by claiming to be his boss. No, the false Red John acted as if he really was or at least believed to be Red John (hypnotized by Jane?).  We only learn afterwards that he wasn't.

My point is Jane isn't John. But he should be. That would earn the show a place in the Olympus of TV shows. Maybe my hopes are fulfilled and at the end of the season another false Red John is revealed. And after three false Red Johns Jane finally realizes that he is the real one pulling the strings in the background.