Effectively impossible to relocate an airline to another country. The regulatory requirements (ownership, registrations, traffic rights etc) would be almost impossible to overcome (you can imagine what Delta/American/United would have to say if they tried to shift to the USA?). Further, and as mentioned above, the HK (PRC) govt would probably cancel any traffic rights into HK, so the airline would be orphaned from the start. It seems apparent that the govt is quietly working on bringing CX down, to either be replaced, or sold. At the current rate of public demonisation, CX will be considered a leper to the HK people quite soon. The party is probably well and truly over.