There have already been significant decreases in Canadian (and likely other countries) purchases of American goods, and travel to the US. The thing you say will never happen, already happened last year.

Jim Beam (the bourbon distillery) said before Trump 10% of their sales were to Canada, and that has gone to nearly zero.

yep, and in some part of the EU the dominant position of Coca Cola has been crumbling for reasons unrelated to the US and many "not a cheap knock off" alternative already exist...