two countries could easily merge,
Quebec would be a problem.... I remember years ago before some independence referendum that the CW was that if Quebec left the rest would end up being absorbed by the US (going from Canadian province to US state).
I don't see Quebec wanting to become a state however (since it would have to commit to English only sooner or later).
Nunuvaat (or whatever it's called) could be problematic as well...
But I mainly view Trump's rhetoric as political poker with russia.... he's playing crazy guy and saying in effect: hey russians, want to get into a competition about annexing other places? We can wipe your nose in it because people like us.... we don't even have to invade!
Trump has a talent for putting russia on its back foot so.... we'll see....
Greenland has no real potential for independence since it can't pay for itself unless it gets into resource extraction (which it doesn't have the manpower for)...
I suspect there will be inceased US presence withing the current status quo.