I think that would just be a pretext to annex Canada much like civil disobedience in the US would be a pretext for martial law and entrenching his position. As a Canadian: nothing polite to say about the USA going forward.
countries will not want military bases from a nation that threatens annexation, will not want their media companies broadcasting to their citizens, will not want to buy their weapons, and will not want their financial system dependent on them
the US just handed the world to the Chinese
on a platter
annexation of Canada would trigger Article 5 against the US