In a number of sectors, I believe it is already the case that companies choose not to trade under NAFTA rules, and simply trade under the WTO rules, and pay the so-called most favoured nation tariff.
It's simply because the bureaucracy involved in providing evidence of origin and tracking content is costly in itself. After all, the most favoured nation tariff might be very low. One company representative told me there's often a Goldilocks content requirement. If you go above that, then you're not maximizing North American content, and you'll actually wind up with less North American content. For instance, if we're talking about electronics, machinery, or autos, you may see more content from Asia or Europe.