I have no doubt DL will continue to hold onto at least one HKG slot for future purposes as well as Cantonese-FA's, but I'm curious whether or not this route would ever be viable again in the future.
CX tried SEA before and it didn't work out, and YVR has much greater frequency.
Time will tell what the future holds I suppose, though as it stands, most of the efficient routings I see into HKG bookable on DL remains to be routed through PVG on MU.