I wouldn't be sad if they pretended the Evil Leapers never existed in the current timeline. Not a fan, really.
But while we do know that Stawpah was a Leaper, I feel as though Al the Bartender's info implies to me that Stawpah was there to work through the biggest issue in his life, which was survivor's guilt, and so he looped around, Leaping over and over again until Tonchi and Pete could be saved somehow. When Stawpah Leaped and fully vanished, my assumption is that he's moved on to the afterlife.
Which could, sadly, indicate that Sam's regret to work through was keeping Al and Beth together, so when he Leaps out of Beth's bungalow... he, too, might easily have gone to the afterlife.
However, since he's so young, maybe he was given the option to continue Leaping; whereas Stawpah was old and worn down and ready to be at peace.
I'd love to see some answers given about Mirror Image because of all of the new questions it brings up. I'm definitely interested in learning more about GTFW, Al the Bartender, and Leapers like Stawpah.