I think some of the A/C capacity is being redirected over the pacific.
CP is operating the vast majority of transpacific service ex- YVR (except for the continuation of AC's YYZ-HKG, and YVR-KIX). CP are taking over SEL and TPE and restarding SYD. I think AC might be operating SHA, but I wouldn't swear to it.
This means the 767-300's are getting pulled from YYZ and sent west, while AC is pulling some 340's out of YVR and sending them East.