I totally knew it was CBI Ron!

He just sent in some stupid random pawn to talk a minute with Jane, to pretend he would be Red John. I didn't buy it for a second.

So
Red John won. He will vanish now with the remains of the CBI, never
heard of again. He reached his goal to destroy tiger tiger and will
probably go on killing in secret again. Until he'll find another - maybe a bit smarter - Jane (and writers) to play with.