Originally Posted by
Endus
NAFTA's not done. Trump and friends are trying to renegotiate it, but if they fail to do so, NAFTA continues; it wasn't expiring.
If the USA decides to unilaterally pull out (ignoring the presidential/congressional authority issue, which isn't settled so far as I'm aware), then Canada and Mexico stick with it between themselves. The USA can establish tariffs and the like, but so can Canada and Mexico. There would be a general cooling of trade between Canada/Mexico and the USA, but the important factor there is that 1> there'd still be a lot of trade, despite everything, and 2> the USA's position is becoming isolationist, and they won't be seeking new free trade agreements with other partners to make up this economic cooling. Canada, at least (don't follow Mexican politics enough to say) is already exploring deeper economic partnerships with the Trans-Pacific Partnership (which the USA is withdrawing from, see above), the CETA deal with the EU, and we're already talking with the UK about some closer economic ties in the aftermath of Brexit, to boot. So the cooling effect isn't likely to hit Canada nearly as much; we'll adjust our trade accordingly, but the USA is essentially declaring that they're hostile to doing so, ideologically.
There'll be growing pains, but Canada at least is likely to recover far more swiftly/readily than the USA is.