I find it humourous that what Cathay essentially wants to do is have one pilot take "controlled rest" in a separate rest facility (i.e. one that will take significant time and resources to be awakened in and return to the cockpit from) when, until recently, this was only allowed for short periods of time (so as to prevent sleep inertia) and in the cockpit (so as to be able to respond quickly to a situation requiring 2 crew input).
They want to able to do it in the A350, an aircraft that currently operates under the extant "controlled rest" provisions and have Airbus sort out all the problems associated with this major philosophical shift from the at-hand-sleep-inertia-mitigating-controlled-rest provisions to the remote-deep-sleep proposal.
And all to cater for reduced pilot numbers. Because they won't be to able to retain or attract crew in the future.