Basically none.

Even if if they do, if QF128 is cancelled QF118 arrives SYD even later than CX162 if you can get on it. They might just hold you in HKG for another day.

With CX with possibilities of spare aircraft it’s unlikely you will have to stay an extra night in HKG which is even more fatal.

Plenty of hotels near cruise terminals - can’t see the issue to be honest and a more restful sleep for the kids.