The idea behind the plot of Kurogane no Linebarrel is a really interesting (and even plausible) concept (minus the giant robots), but I think what's most likely to happen is an economic and political collapse as the UN and NATO, along with most of the world, pull away from the US and its radical support of Israel.
I foresee a world war in the not-extremely-distant future (probably won't happen in the next five or ten years), with the US's main enemies possibly being old allies such as Germany, France, and England.
If that is how SHTF ends up happening, you would do well to get to a rural area. North America is a nigh-impossible continent to invade due to its placement and sheer landmass owned by only a handful of nations, but that wouldn't stop ranged strikes or covert point insertion from putting big cities in crutches, and quickly.