Oh, I don’t believe for one second that Sam would ever return home permanently! And I consider myself a very hardcore self-respecting fan of the franchise. Traveling through time, putting right what once went wrong and making the world a better place, is Sam’s purpose. He’s answered the call to a higher purpose much greater than his own happiness. What is he going to do if he gets home, sit behind a desk and calculate equations all day? I seriously doubt Sam would ever be content doing that from day to day. That’s just not who Sam is. His true gift is being selfless and helping to change people’s lives for the better. You gotta remember, when Sam first leaped, he didn’t have a family to come home to. He wasn’t there when his father died. Even in the new timeline, Sam made a conscious choice to leave Donna behind for something far greater…and it was sort of implied in “The Leap Back” that she knew this deep down inside. She told Al, “Sam couldn’t do what he has to do if he remembered us.” It’s the very definition of the Hero’s Journey. The journey is not always one that they want to take, but one that they need to take. Look at pretty much any superhero story: the hero always goes through a moment of weakness where they want to quit because of the effect that their calling has on the people that love them. The current series has pretty much clarified at this point that in order for Quantum Leap to work, it requires sacrifice: a mission that is much bigger than oneself. And in those same superhero stories, the hero’s loved ones almost always come to a mutual realization that the sacrifice being made is the very reason why they love that person so much.Which makes it even more unbelievable - the ultimate do-gooder not returning while possibly knowing all his close family and friends have passed, it just doesn't make any sense to any real self respecting fan of the show and in the end a kick in the nuts to said fans.
Sure, Sam could go home and be with his remaining family and friends, but would he be truly be happy knowing that in doing so, he’s not out there helping other people throughout time? That doesn’t mean we never need to see him again, but I’m 100% certain that he’ll never actually return home for good. It would just completely go against who Sam is and why we all love his character so much. Think about what he said to the Bartender: “I’d like to go home…but I can’t, can I? I’ve got a wrong to put right for Al.” I think he instinctively knew that by doing that, he’d be changing the timeline in such a way that would make it impossible for him to return to the same reality he left. Giving Al happiness was more important to him than his own happiness. That’s what heroes do!