The incoming administration is committed to wide-ranging tariffs against its largest trading partners, including Canada. There is a belief among some in Trump's orbit that this will "pay for" massive tax cuts (particularly for the super-rich).
This is going to happen. Various noisy distractions about border security were just cover for an economic belief that tariffs are free money.
USMCA has a high probability of being abandoned in the very near future. The proposed tariffs are in absolute and complete opposition to this trade agreement (which it should be noted was negotiated and implemented by the last Trump administration), and anyone on TN or other USMCA programs should plan accordingly.
Trump said until and when the border is secured. Canada did propose plans for increased spending on the border security, even though it’s not really a concern. It would be interesting if US still imposes tariffs (which might very well do, according to the latest meeting between the trump and Trudeau teams).