There will be a few leaving CX, prob the early retirees. A few locals from KA to the 330 or 320.
For the rest, why give up 90% schooling subsidy, 100k housing (b scale)
OT, and union protection for the unknown?
Ultimately HKA is for the young wannabe not the mid career types from CX or for that matter ka. A face full of jet lag, thats all.