AC*SE, you raise an interesting issue by suggesting we could still get oneworld partner miles flying AC/CP flights bearing AA codeshare numbers on intra-Canada flights, after Cdn leaves oneworld. My understanding of codeshare rules would make this impossible unless those intra-Canada flights were connected with an AA itinerary, i.e. LGA-YYZ-YEG. AA -- or any other codeshare partner -- is not, I beleive, permitted to sell YYZ-YEG on its own, but only in conjunction with a flight from the home country of the carrier (i.e. the U.S.A. in the case of AA) or from an intermediate point from which it has carriage rights into Canada.

You wouldn't find YYZ-YEG-YYZ bookable as a codeshare in AA's computer without that U.S.A. linking flight. (Otherwise, they must be booked under the AC or CP codes.) I tried to do just that during the 100K promo, thinking it might be possible to pick up an intra-Canada codeshare segment with an AA or QF flight number (YEG-YVR for example). Couldn't do it unless it was part of a larger itinerary starting in the US (for AA) or Australia, New Zealand or Hawaii (for QF).