You've made the argument, again, it's false to suggest the statement 'Canadians would be richer in a specific trade deal' implies that every Canadian would be 'better off'.

This is 'basic communication'.

In much the same way many people are making the argument 'Brexit will cause UK citizens to be poorer' (however debatable in the first place) - obviously doesn't imply that the case will be the same for all UK citizens.

Finally - to your specific point - Canadian famers would be economically better off financially, because there would be a massive buying spree for all assets that were otherwise protected.

If they tried to 'hold out' of course they'd be put out of business, but from a raw economic value perspective, they'd be 'richer' no doubt.

CIBC/BMO/Desjardins - all the major banks, Bell/Telus/Rogers (Telcos), CTV/Global (networks), Loblaws (Groceries) etc. etc. would immediately be acquired or merged into larger American entities. (Except in the rare possibility that the 'smaller' Canadian entity made a deal with a Hedge Fund for a massive leveraged buyout of their much larger American peer, but that's unlikely)

Of course, one might argue that would be a 'giant disaster' for Canada, even as Canadians had immediately higher incomes and GDP/capita - and the argument is essentially derived from nationalism. Hence, the hypocrisy of people lamenting that the UK doesn't deserve a degree of material sovereignty.