Geopolitical / economic activity doesn't happen on the basis of friendship.

The US has exploited Canada for decades. Sometimes it's been somewhat beneficial for some part of the Canadian working class. Other times not.

China will do the same. Just from a further distance.

Americans who like to convince themselves that the US has been doing charity work for us are delusional. They've benefited from discounted resources and cheap labour.

Now China will benefit from that instead, and the US will look internally for cheap labour of its own. American workers who think they'll get a good deal out of cutting Canada out of the equation... again, delusional. Their necks are first on the chopping block. First through paying more at the cash register because of tariffs, and next because the Trump admin will be coming after their salaries next.