I don't think the Administration will resort to across the boards tariffs. I agree that would tank the economy. There is a benefit to having an unpredictable President issuing threats against our neighbors. I guarantee you it will get their attention and they'll act accordingly. It's unconventional but I predict it works.
This also demonstrates that the center of world power currently resides in Mar Lago and not DC.
Ok, but let's consider the possible outcomes. What if, hypothetically, it doesn't work? What if Canada and Mexico call his bluff?
What does he do then? He's got to respond in some way, or the whole world will follow suit. So, how does he respond?
Trump is the antithesis of Teddy Roosevelt's "Speak softly and carry a big stick." At some point, if he keeps going, however, he is going to have to pull out whatever stick he has. Because "being unpredictable issuing threats against our neighbors" only works for so long, without following through on said threats.
At best, unpredictability is a short term solution. But, when dealing with unpredictability, one has to also factor in what can go wrong vs. what can go right. Keep in mind, Trump has had the last four years to form his plan for this administration. But, so has the world. And, based on who Trump has around him in his cabinet, there is a good chance that the world can out-maneuver him. So, when things don't go his way, again, how does he respond, and what is the impact on all of us when that occurs?