The following links are all you need to see who Red John will be....
Sorry it's not some overthought ridiculous theory....I admit those are fun to read.
        So here are pics of nick nordella and xander berkley.  And finally a short plausible theory.
One can obviously see that nick nordella is going to be a young McCallister..... 
  
http://images.buddytv.com/btv_2_800033859_1_434_593_0_/xander-berkeley-in--.jpg

http://www.ddoagency.com/images/artists/artist_1301425352_43_l.jpg



http://www.whoisredjohn.com/See-a-theory-Red-John/11150