Yeah, to be honest I would have liked to see the kids stick around as well. For what it's worth, the thing they say on the very last page ("Even at the other end of the earth, we'll always love you") actually means "We'll love you forever at the other end of the earth" literally (i.e., that they will be at the other end of the earth rather than being nuked from existence, like the rest of the chapter might suggest), which might imply that they get to stay around through Lin Yuan in a way. ¯\_(ツ)_/¯