Canadian&US Federalism and a threat to the survival of either country. Need ideas!?

I have an assignment for my Intro to Political Science class... I am not looking for answers but for ideas on what to write about. The assignment is copied below.

I need ideas about what threatens the survival of either the United States or Canada and whether it exists in the other country or not. (I can explain whether federalism exacerbates or reduces the threat).

Does federalism threaten to break-up multinational states? In addressing this question focus on the United States and Canada. Both of these states have federal systems of government but are quite different in the powers that they allocate to national governments and provincial/state governments. Identify a threat to the survival of either Canada or the United States and tell us how federalism has played a role in subduing or exacerbating this threat. In addressing any threat to the state that you have chosen, tell us whether the threat exists in the other state and if not, tell us why. For example, you might consider addressing the push for sovereignty in Quebec and the role that federalism has played in enfranchising or subduing pro-sovereignty forces. If you address this issue, tell us why a similar problem does not exist in the United States (why haven’t Florida, Texas or New York threatened to secede).

Any ideas are greatly appreciated! Thanks!