CX(Swire) don't send you an employment letter till as late as possible as they do honour their offer of employment. During SARS they paid salary to those they had offered jobs to, but had not employed yet...even though their courses were delayed. CX don't have a history of retrenching.
Caveat - I am sure you have peers/friends in CX that can update you on the less than transparent upgrade process and they will give you a better idea of any hurdles you may face in future.
good luck