And presumably if every nation is at war with the US, any military bases the US had on dependant nations would've likely been closed years prior to the war (Which in the case of israel, is improbable but we're discussing the war itself, not the cause.) in preparation for it to avoid equipment and manpower losses.
This presumably is not a safe assumption. I, for one, have been operating from "World War three starts completely unexpectedly, as if at precisely 12 GMT, the entire world became possessed of the notion of killing America" because that assumption is no less realistic than "Mighty pacifist Costa Rica decides America needs to be taken down a peg". If the build-up takes years then it's an entirely different question. I assumed the former because we actually know to a limited extent what military forces the world and the US can bring to bear today, whereas what they
could bring to bear in the future is more hypothetical and harder to answer.
Foreign nationals living in the US?
Why would they act suicidally? I mean that makes even
less sense then Canada invading, somehow. Maybe they don't want to strap a bomb to their chest and run into traffic or be executed by firing squad or abducted by the FBI in the middle of the night or whatever! But perhaps I am being too reasonable here.
I think the scenario is more interesting if not literally every non-American human being on earth is filled with inexplicable bloodlust, but each to their own I guess. Either way, though, I think defining the terms of the scenario is important. It's already such an unrealistic scenario that basic assumptions like "people would rather be alive than dead" are not safe unless actively defined as such.