Looking at ITA (and airliners.net), looks like no more DTW-HKG nonstop after 8/29/12. No idea if it'll be moved to another city, made seasonal, or just canceled. Also see http://airlineroute.net/2012/06/23/dl-dtwhkg-sep12cxld/
It might be seasonal, or maybe they're going to move it to another market? I can see JFK-HKG, but CX has that market covered, and it'll be tough to compete with that. I could also see LAX, given that they can do connections from all over (as well as from AS now that T6 -> T5 connections are possible). DTW-HKG is a very long flight
