I think that last scene was more about Randall finally being able to see his ghost kingdom with his real parents, instead of the librarian and the meteorologist.
It's a term coined by a therapist working with adopted patients. In the group, someone said she'd moved on from hers. Perhaps now that Randall can see his real parents in his fantasy, he'll be able to move beyond it, too.
I also hope that this isn't a one-and-done about the bros reconciling their past. I think the emphasis was on Randall getting what he needed here, but there's plenty more than saying Jack was proud of Kevin that he can (and hopefully will) give to Kevin.