From a trade/foreign policy perspective, no, it makes no sense. From a long term growth of the USA perspective, it makes a lot of sense. As the Earth heats up, the equator will become less habitable, and the poles will become more habitable. Canada and Greenland have a low population density because of their northern climate, they have resources that are un-extracted because it is not economical to pay someone to live on-site. Every year it gets warmer, and that land becomes more valuable.

For the record, I'm not against Canada becoming a new State, but I am against using military or economic strong-arming to sway that decision.