The essence of this article (& I agree with its thrust) is that Trump can materially impede the day-to-day operation of NAFTA as it governs trade between the US, on the one hand, and both Canada & Mexico.  However, the scope and effect open for such unilateral Trump action are vague.

It follows that the ensuing chaos that would ensue at all stages of production, marketing & sale in most industries would be severe & prolonged not only in Canada & Mexico but also in the US because the extent to which NAFTA terms continue to apply to 2 & 3 nation production, marketing, and sale chains would take years to sort out.

While many GOP & Democrat elected officials & supporters oppose NAFTA on a vague basis, many others in both Parties would strongly oppose the self-inflicted damage that unilateral action by Trump would cause.