Wouldn't DL risk losing the Haneda slot it currently has if it dropped MSP-HND? It's not like they could just switch MSP-HND to ATL/SEA/DTW/JFK-HND at will, so while I won't say "never", I doubt DL will just drop MSP-HND, even if DL or KE launch MSP-ICN. Additionally, the flights would serve two different markets. MSP-HND is all about O&D traffic to and from Tokyo, with few if any onward connections from HND. MSP-ICN would be about both local traffic to ICN as well as facilitating onward connections via KE.