I believe this is the new world order. A few highly trained teams with overwhelming technical support. Not a man-to-man-shot fired.
We refuse to surrender, send as many of our people into the bush as we can, and let Trump bomb our cities to ruin. He’ll conquer a wasteland that will be an endless sink of blood and treasure. Even taking all our resources won’t make up for the loss of everything else that makes Canada valuable.
Perhaps not a direct invasion, no.
But certainly a “limited incursion” in order to replace the government with one more in line with MAGA would not be out of the question.
Just a quick overthrow of the elected government (for the good of Canadians of course), and a replacement with a handy Quisling or Petain. Pierre Poilievre would be a most excellent candidate.
They’d think of it as a quick surgical strike to get Canada (and it’s resources) fully under US control.
Of course, the subsequent actions of the Canadian public would come as a complete shock to them, as they’d be sure that they’d be welcomed as wonderful invaders.
I would say “very nearly none,” and almost certainly none within the higher end of the officer corps.
Possible, but I do not believe Canada will take that path. Imagine the spectacle of abandoning Montreal and after the 2 month traffic jam subsided, where would they go.
(my ellipsis)
But you wrote this in post #34 above:
Would you be better off under US bombardment or house to house attack?
Yes, I believe Canada will avoid a WW2 confrontation. That was the point of both posts.
Each generation of officers needs a war. A near bloodless take over of Canada is a tasty prospect. Beats Grenada.
I can only point to my post #2 in this thread. I’d have to see it – probably several times – to believe it.
Cottage country, campsites, smaller towns and villages, farms. The US would like to cheap out and only have to occupy the major cities, counting on that to hold the rest of the country. Make that impossible. Disperse as much of our population as possible, and make them garrison every podunk hamlet there is, lest we use those places to plan partisan attacks.
We’ll plan partisan attacks anyways, though, because 20 Marines in a town of 200 hundred people is a bit easier target than 2000 Marines in downtown Ottawa.
We were faced with that during the Cuban crisis, but in reality we could not move (silicon valley). Our population density is too great and we are totally dependent on the commercial networks for food, energy and income.
Or, successfully trash our economy to the extent that he would expect us to plead for a US takeover.
How low would they have to take it though, for us to accept US culture, US politics, US working conditions, US healthcare, US attitudes to civil engagement, US treatment of minorities, US gun culture, all of that?
We’d have to be literally starving en masse for that to be an acceptable alternative.
That’s not what was imagined in the OP. The post of @Euphonious_Polemic upthread also discusses the more modern approach, where the Canadian culture remains intact. Very little changes day to day as the government is in slow transition. Not unlike New Mexico and Utah.
That’s a question that I have been asking myself a fair bit lately; IMHO it’s unpredictable and possibly unanswerable.
Or, how much would we be willing to sacrifice?
But we Canadians also get a say, war is democratic like that. Like I said, the US will want to do this cheap and easy, but we won’t let them. It might start off that way, but Vietnam started off with just a few “advisors”, too.
They’re not even threats, just brainless ruminations from the Orange Fathead. This is all just nonsense.
There are a couple of basic things that some Americans, most notably the Orange Doofus, don’t realize about Canada and Canadians. One is how deeply and adamantly Canadians are opposed to any such move. Trump thinks most Canadians would welcome the “privilege” of becoming Americans. He couldn’t be more wrong.
The other simplistic bit of nonsensical babble about “the 51st state” is that governance in Canada is intricately and deeply structured along provincial jurisdictions, reflecting vast regional differences in culture and economy. Making the whole country a “state” from coast to coast would be an administative nightmare that could never possibly work. The whole thing is the most ridiculous folly. Just because you have a big army doesn’t mean that you can make impossible things happen. Just for starters, Quebec would instantly declare civil war.
It was the position of Bush the Lesser and his coterie that the “Coalition of the Willing” 
would be greeted with flowers and loud huzzahs on the streets of Baghdad. Perhaps my memory is not under sufficient control, but I don’t recall that happening.
And Saddam really was a cruel and repressive dictator, whereas the vast majority of Canadians love their country, their system of social democracy, and their peaceful existence.
So is his incursions into cities. His rejection of birth citizenship. His destruction of science in government. His acceptance of a 747 gift. His cabinet. His administration.