To begin with, this intro is not a theory as such, but I've read elsewhere that the famous Red John voice is actually done by Simon Baker, not whoever plays the character that will be revealed as RJ. Plus there is that YouTube video doing the comparison in voices, and unless it's a perfect imitation, it's definitely Simon Baker's voice in the limo (season 4 finale). The season 2 ending sounds like it could be done by Baker too, he is pretty good with voices (i didn't realise he was Australian until i saw the DVD bonus features of Season 1).

Will be interesting when RJ is revealed if the actor can actually do the voice, or if they have to dub Baker's voice over when the person reveals their dark alter-ego. 

One final thing, my guess is Haffner. The tracker location in 6:01 stated that he was "In Transit", and a car did pass Lisbon as she was entering the house, maybe it was a disciple with Haffner's phone in the car to distract attention? Add that to the visualize angle, the physical description, the numerous throwaway clues (Red Barn).