I think it's possible for C.C. to live... it all depends on what her wish is. We keep assuming that if Lelouch takes her code, C.C. has to die. But all he really has to do is grant her wish. I get the feeling that C.C.'s wish is to be liked for who she really is (judging by what her Geass was when she had it - since everyone in the show has had a Geass that somewhat suits their needs and desires, how she acted as Moe C.C., and how she acted when Lelouch figured out her real name and she asked for him to call to her with her real name like a lover would). If that's the case, Lelouch could still obtain C.C.'s code by simply accepting her loving her, turning C.C. mortal. Then Lelouch would expect C.C. to leave, since the contract has been fulfilled and she no longer would have to stick around him to be his partner in crime. This would be the perfect case for C.C. to say her spoiler line: