Guy Gardener wrote:
"My Dad is lost in time and I'm going to get him."
IIRC, that was actually supposed to be the topic of the QL sequel briefly discussed a few years ago. Sammy Jo (the daughter Sam fathered while on a leap, who is a genius-level intellect just like him) joins the project and tries to help bring Sam home.
As for Sam never returning home: Agreed, that is sad, but the 'rules' established in the final episode prove that he's doing this because he wants to - he must feel that his work will never be finished and so that's why he won't stop leaping. Although it's just as well that his memory is swiss cheesed because then he forgets that he has a smokin' hot wife back home.