I think the backtracking back to CPH via ARN is not completely disappearing. I have done MMX-ARN-CPH-IAD and will do MMX-ARN-CPH-HKG. It's totally ridiculous and I don't know how much SK gets if 400 SEK of the fare goes to the Swedish government. The funny thing is that I was surprised that SK dares to do that in Sweden as some Swedes are very concern about how flying pollutes the environment.