Once more confirmed that there ain't no coming back from RJ:

Will any element from the Red John storyline resurface or is that completely put to bed?
It’s put to bed. I don’t want anybody to think we didn’t get the right guy and he’s still running around—because he ain’t. There are story elements that pop up that resonant with that story, because something as traumatic as that is never going to leave you alone the rest of your life, but Red John does not come back in that way.

From http://insidetv.ew.com/2014/11/24/the-mentalist-final-season/

A shame - but we all know this show died last season. We'll alwasy have 3 great seasons and some great episodes in seasons 4 and 5. Keep to your theories, most of them were better than Hellers ending.