Sorry, my initial post is a bit confusing. It is actually the CPH-NCE return flight that has been rescheduled.
NRT-CPH and CPH-NCE are both once daily flights. I imagine they will try and change me to a 2 stop itinerary changing at CPH to another *A carrier (as opposed to making me wait overnight at CPH). I will ask if they can simply put me on another *A carrier on the entire return leg, say NRT-ZRH-NCE - though won't hold my breath.