It appears as if they are setting up for Lisbon to leave too. Whether she ends up with Agent Pike or Jane, I do not know. But I suspect she will end up with Pike and Jane will be her biggest fan and supporter. They're too good of friends to take it to a sexual relationship.
The show will final out with Jane being content that Lisbon is happy. Which will make him happy. All the other cast members have left, and he will go on with his life.
Just like the other poster said, the show has moved on from Red John. Red John is good for reruns only.
The Mentalist is going to end on a good note. The Red John hunt went on for years, and ended months ago. If you want a secretive type serial killer action type setting, I advise you to look into the Zodiac killer.
Patrick Jane avenged his wife and daughter's death. He is moving on with his life.
I suggest all of you do the same as well.