I'm not from Canada, but my take is that given Canada's economic reliance on the US, any "divorce" would cost them more than anything they could find anywhere else. However, I also don't think the PM there can simply separate his country from the US by simply giving a speech, although he can work to foster closer ties with others while still trying to make it work with the US.
Canada has a dysfunctional domestic trade economy where it’s often easier to trade across borders with the U.S. than it is to trade across provinces.
Simply eliminating a lot of those domestic trade barriers would create more economic wealth than what Canada would lose by ending trade with the U.S. completely.
Of course in practice it won’t be that easy and the finances don’t usually materialize that easily, but the point is Canada has options for growth that are fully under its control.
The only sector where this is generally true is liquor. This is significant, but not massive.
Inter-provincial trade barriers for labor, especially licensed labor are also quite onerous. But it's still easier for a Quebecois tradesman to work in Ontario than it is for that same tradesman to work in the US.
If you watch his speech and the follow up interview you he answers that directly (https://www.youtube.com/watch?v=kDMyeGQm3NA @ 17:50). It's a good watch, better than the past 10 years of daily coverage by American media of what their dumb president and ex president is ranting about.
I am in the start up community in Canada. I can tell you that after the first threat from Trump every federal program to help tech start ups immediately pivoted to Asia and the EU. Before he started yapping, we were connected to Canadian representatives in the US, meeting about markets and opportunities. Now all programs are directed at forming partnerships elsewhere.
Your logic is exactly why Trump's gambits always work. Everyone knows that individually standing up to a bully is a good way to get the raw end of the deal; so nobody stands up and the bully continues racking up wins.
It's certainly not guaranteed, but taking an aggressive defensive stance is the ONLY possible way to stop having your lunch money stolen.
Canada will suffer greatly, and possibly much more than the US. But appeasing US, in the position of Canada, is akin to trying to reason with a wife beater.
You don't reason. You remove the victim from the hands of the aggressor.
It will cost a lot of money, and the Canadians will suffer greatly. But the alternative is to join America, which Canadians have stated don't want to.