I also got hit with a cancellation of DL's DTW-ICN route (actually the other direction) on an award flight. There's not much you can do when they cut service. DL should be very reasonable in routing you however you want on their metal, but I honestly think the routing they gave you with the 747 on DTW-NRT is about as good as you're going to find. Since DL can't open space on KE, your only other option, unless you want to add another connection, to keep your ICN-KIX flight would be to route through SEA and fly SEA-ICN on the DL 767. Even then, you'd probably need to add a domestic connection unless you can DCA-SEA space on AS since DL doesn't fly it non-stop.

Here's my thread if you're interested in reading. http://www.flyertalk.com/forum/delta...king-help.html