1. It's all about syndication. In sorting this out the first thing to keep in mind is that The Mentalist is not a novel or an indie movie, but a rather large business enterprise. Simon Baker, for example, got a $30 million contract for seasons five and six. That only pays out if the show does well in syndication, and the show won't do well in syndication if a Red John is unveiled that kills the appeal of the show. That means that you can be sure Red John won't turn out to be one of the attractive heroes of the show - it won't be Patrick Jane or any member of Lisbon's team.
2. They may never tell us. The Fugitive was a long running TV hit in the 60s, and everyone thought it would dominate in syndication. It flopped in syndication because the final episode solved the mystery by allowing the protagonist to finally catch the one armed man who had killed his wife. Once the mystery was solved, no one cared about seeing the reruns. That has haunted producers of long running TV mysteries with long running plot arcs ever since. You will remember that The Sopranos ended with a deliberately inscrutable and vague ending so as not to put a cork in it. The producers might make that same choice here.
3. There are lots of characters it could be. If they choose to name a Red John, there are lots of candidates left open. It could be anyone from Brett Partridge (seems a bit young and light, but who knows) to Ellis Mars (ditto, but he could be playing dumb), to Virgil Minelli (a bit too likeable, but not so likeable or core that he's out of bounds), to Brett Stiles (certainly capable of it on several levels and definitely twisted enough) and on. It's a fools game to think viewers can nail it with certainty this far out.
4. My gut - go with the paranoid choice. I like Robert Kirkland as Red John, although I recognize he's just one of many possibilities. He meets all the essential criteria, he's the right age, he's figured into the plot appropriately, and so on. Most importantly, to me, it fits into the zeitgeist of the age, which is paranoid suspicion of everyone in any kind of power. Who better to be a deranged serial killer than a Homeland Security operative charged with protecting us from evil enemies? Who could be better positioned to stifle investigations than someone who can reach out to all the black ops operations of the most powerful government in world history? Because of that zeitgeist, it can be done in a way that doesn't kill all the suspense - yes, Red John is unveiled, but we can be left wondering what even darker conspiracy is left in place that nurtured and protected such a monster.
