Earlier quoted context omitted.
It's incorrect to think of Canada as being "cornered" here nor having "nothing to lose". It's the US that's isolating itself. Canada isn't 'cornered'. It has the entire rest of the world to talk to and make deals with. It has everything to lose by continuing to rely on the US, which is why you're seeing such a hard pivot toward Europe and Asia.
I wouldn't color relying on a historical ally that either produces, or is the transit corridor for, most of your food with "everything to lose". The current trade spat is an issue, and Canada should react accordingly, but the reality is that, even with tariffs, the US still represents a very profitable trade partner, especially when they can levy tariffs of their own.
Tariffs are only part of the issue. They seem the be the first USA step meant to weaken Canada economically before USA proceeds to steal from from it.