Based on the fates of various comparable civilizations throughout history, I have made a map detailing what I expect will become of the nations associated with North America during the coming decades.
The most obvious conclusion is that the United States, being a republic, will fall as all republics are doomed to fall. Like the Western Roman Empire before it, the United states will fragment into what will likely be petty kingdoms, some of which the british empire should seek to annex so as to expand our influence. The remaining regions of what was once the United States will start to form larger nations through war, resulting in something similar to what is depicted in the above image.
At the top right corner of the map is essentially a warning to Britain, for there are those who are foolish and believe that monarchy is obsolete. Looking throughout history (up to and including the present day), however, will reveal that republics are rife with turmoil and will inevitably crumble before long. Look at the chaos, violence, and injustice that plagues the United States of America even as I write this, for it makes any problems we have appear trivial by comparison.