I'm not planning on writing any such thing (although stranger things have happened), but it's fun to hypothesize.
Teyla = obviously a female Cassiline
Sam = member of the D'Angeline peerage... Comtess de Lantia in Siovale?
Rodney = scholar from Caerdicca Unitas... maybe come to set up some version of the University of Tiberium in Terre D'Ange?
Ronon = Camlach. Definitely. I can totally see one of the more 'cultured' D'Angelines accusing him of "thinking with his sword"
Carson = The Littlest Alban?
Lizzie = I'm not sure. I think she was a diplomat of some kind who would up trapped/held hostage in Skaldia
Keller = no clue
John = I'm having trouble here. I'm tempted to make him a Servant of Naamah, but I really don't think he's the man-whore that some people make him out to be
Anyone else familiar with the series feel like taking a stab?