I think Red John is possibly Lisbon's nemesis Tommy Volker because he is a multi billionaire which means he can get people to kill for him like we have already seen and he just lets people get there hands dirty while he can walk free just like Red John.Many people are afraid of Tommy Volker because of what they can do to him and thats the type of person Red John is.Like Red John Tommy is really smart as Jane has said and is the reason why Lisbon can't catch him.I don't know whether he is working with Robert Kirkland but he has warned Lisbon about Tommy because he is dangerous and that is exactly like Red John.He is the right size,build,age and has straight hair like Rosalind describes I know that is a lot of people but Iam saying it makes him a possibility.We don't really know much about him but when he reappears I will be able to make my full mind up by looking at small things of what is known about Red John such as his favourite music is Bach and he is a tea drinker.