That would be highly unlikely. SOU (like BOH which also only has one route) is operated by easyJet Switzerland, a separate airline that has its own route strategy team. DS fly to several destinations that are not on the U2 route map. easyJet themselves have not yet entered the SOU market, and almost certainly won't do so as they wouldn't want to risk losing passengers from their BRS and LGW bases. You're also forgetting that DS haven't even operated their first flight yet from SOU, and they'll want to test the waters for a year or two before considering adding any new routes.