Canada being a Confederation of Provinces could separate easier than the states of a republic.
Greater Toronto and Central Montreal are the problems, because they have so many Federal seats, they decide who becomes the government. It is like two little pieces of fly shit on half a continent that rule the whole rest of nation. If they were removed from Canada they would fade away in very little time.
Even on a slightly smaller overall scale: You can take out any given city in Ontario, up to and including Ottawa, and still gain Ontario in its entirety, but if you cut out Toronto, even just the basic core of it; removed from the entire, surrounding GTA, you can *never* gain Ontario.