The events discussed are recent enough to allow quite a bit of study.  Had the US not purchased Alaska the eastern boundary sought by Great Britain would have held, so much of the interior of what is now Alaska could be part of Canada.  The rest of Alaska might well have been claimed by Japan in settlement of either of the two wars Japan won against Russia.  From that idea almost anything could have happened.  Japan would have had a better position in WWII, perhaps immediately taking western Canada.  Irish Canadians were inviting Hitler to take Quebec and the Maritimes, so the outcome of WWII could have been different.  On the other hand, Russia might have been able to keep Alaska and therefore even current world balance would be different.