Exactly nitpicker, and how do you think QF would feel losing their brand new A330 commanders who just left the 747 6 months ago? Who would replace them? Perhaps a CX FO might go and get a direct entry job as an F/O with QF for the chance to live in Australia perhaps QF would up their command pay to stop commanders leaving with a brand new A330 endorsement. Perhaps CX commanders would leave to join QF on their higher pay.
CX wont give a command to just anyone. I'd say a lot more CX Capt's would leave for higher pay or a better lifestyle, if you could join a home carrier on the same or similar pay which CX capt or F/O for that matter would stay in HK?
It will never happen as no airline management would ever ditch seniority as they know it stops people leaving and keeps pay down which is the goal, it's only got to look good at the beginning ie ICadets!