SQL has announced it will start SIN-EWR nonstop flights - the longest in the world - at 9535 miles / 15345 km in the near future, using the A350 ULH. (With no economy class, however).
As such, this would make YYZ-SYD flights possible (as well as YYZ-SIN flights). By extension, could this this possible mean YVR losing its Canadian monopoly on Australia routes to YYZ?
I doubt this would be doable, as the EWR-SIN route has no economy class, and YYZ-Australia would presumably need an economy class (B789) to make it viable. YYZ is not NYC.

Nevertheless, I just hope that there are areas of the world where YVR would maintain soveregnty in the Canadian market. I'd hate to see YYZ infiltrate YVR's own "space."
Unlikely: yes, I think. Possible? I'll let the professionals answer that one. But hey, YYZ just got Manila nonstop, so could it ultimately eat further into YVR TransPacific territory?