Here is a wild theory that popped into my head the other day.
Brett Partridge has always been the number one suspect for good reason, because Brett Partridge WAS Red John.
He is really dead. He was killed in Episode 1 of Season 6 by a new unknown killer who may or may not be a Tiger Tiger member.
We will see the other suspects all be killed off or eliminated from being suspects (even though they have shady aspects to them) as the truth emerges that it was Partridge all along.
This moves the show on to a new era with the question changing from "Who is Red John?" to "Who KILLED Red John?" and how should Patrick react to the killer who was able to "get" Red John and rob Patrick of the chance of vengence (which is what has been driving him for years).
The killing of Partridge did not seem like a Red John killing, especially with what happened to Lisbon. Have there been any confirmed Red John killings since Partridge died? The Lorelei video suggested that he would be going on a killing spree, but that has not happened.