There is a history of EI starting and stopping the CPH route, hopefully this time they will hold on. I hope that the US connectivity will render the route sustainable.
I suspect SK and DY will exit sooner than EI and FR. EI will hold out, if their approach is to exit in the face of extremely low fares like the 60c I've just paid for return, they may as well take that approach across their network and so routes like DUB BRU would be canned too. I can't see that happening.
EI are quite resilient, time has shown that.