Trump is in a win win scenario.

He is in control of the world's most powerful military. He is the main force behind NATO. He wants NATO members to increase defense spending. He wants to strengthen the border defense between Canada and US to stop illegal movement. So he says a bunch of things that will piss off world leaders and put them on the defensive.

The cons: He looses some friends temporarily. The US will be less popular in the world which is nothing new. No one will actually go to war unless the US strikes first so it's just unpopularity they have to worry about.

The pros:

NATO members get worried and spend on defense.
Canada strengthens border defense.
Europe becomes more militarized.
Economic sanctions could very well force Canada to become part of the US and then Canadian resources can be raped to fuel more US expansionism.
If Canada goes to actual war the US can handle it but many others would die, living lots of housing and infrastructure for the US.