I thought "the adventure continues" ending was what everyone else got (other than Michael and Book, and in their cases, the "this is them in old age" ending also included the information they had lots of adventurs and a good life in those decades). As I said, I suspect TPTB deliberately didn't tell us about anyone else's futures (except a brief hint re: Tilly) so they can use the characters in whichever way they want in otherh shows.