Your second and third options, absolutely. For the first, it's a matter of whether the sovereignty of US could be credibly threatened militarily, which would i

Your second and third options, absolutely. For the first, it's a matter of whether the sovereignty of US could be credibly threatened militarily, which would is hard to imagine without a long, long fall in its military power. It's not the superpower status, it's the absence of credible military threat against it. Canada or Mexico (or Finland, or Vietnam or North Korea) can't guarantee the absence of instability by their military heft alone.