You would think that YYZ with a 98% load factor that there would be more room
on the route.
The same could be argued for UA on EWR. While I understand that to some extent the Canadian market has "died out" we are actually seeing an increase in flights across the pond. Next summer MAN will have Air Canada Rouge, DUB gains x3 new services to YYZ aswell as the resumption of SFO. This along with new USA flights from MAN and EDI. Even LGW gets a link to BOS next summer.
BHX has been very vocal about gaining a new link to the US and for whatever the reason they've been unsuccessful. If the market isn't there then surely the BHX team would be the first ones to realise?