I flew this route back in April/May (Roundtrip HKG-CAN); Both legs were completely full, most pax were connecting rather than originating/terminating in HKG. In fact one of the flights was scheduled to be operated by a KA A321 but was switched a couple weeks before the flight to accommodate the demand.
Great way to get between the 2 cities, and use the CX lounges in HKG if flying J or have status. Also a steal if you use Avios.