There is no doubt this is the true and final ending.

What a crock of shit.

In an interview with TV Guide, they specifically mentioned that Bruno Heller "chose" McAllister to be Red John about a year ago!!! - Meaning Heller had NO PLAN about who Red John was supposed to be from the very beginning.  That.  Is.  UNFORGIVABLE.  He never had a plan, never had a story.  It's why NONE of our questions will ever be answered ("He is Mar") - THERE WERE NEVER ANY ANSWERS!!!  He was making it up as he went along.

I will never watch this show again.