Ummmmm.....That's not going to happen. None of those things.
First of all hiding and hoping for the best is not a strategy. Running away and living far from others is not a good defence. It's no defence at all. And what will you do when they attack?
Even if you aren't hit, you are going to ignore the deaths of your countrymen? You won't want justice?
With all due respect, that is just whack. That reminds me of racists and Neo-Nazis and all those freaks whose solution for life's problems is to blame other people (preferably those who look different), move to a compound in the middle of nowhere, hope for the best (and/or the worst) and indoctrinate their children to do the same.
Short of some sort of armageddon scenario, there is not going to be reverse urbanization, with everyone moving back to the countryside.
Also, stopping immigration altogether is impossible. As long as we are wishing, I wish for heaven on earth.
Furthermore, even if America forgets the world and stops doing things and stops trading and spreading culture and everything else they do that people hate, the world will not forget or forgive.
Furthermore, technology needs cities to operate for a large number of reasons. Cities are also opportunity cost efficient, when you are looking at the big picture, so it's not likely that people will choose NOT to live in cities.
Doing nothing is no way to defend yourself, no way to win a war, and is unAmerican and unWestern.
If you believe your enemy may use fire as a weapon against you, you build in stone.
In the future--thanks to ever developing technology--keeping WMDs (atomic, biological, chemical) from terrorists will be as hard as keeping fire from them.
So, we should stop living in a manner especially vulnerable to the weapon of our enemy.
The safe manner to live, is to disperse population.
Were there a handful of Americans per square mile, why would anyone go through the bother of obtaining a WMD to kill a handful of Americans, when a simple gun would be as good?
"so it's not likely that people will choose NOT to live in cities."
They have no choice but to live in cities. They can't go back to an agrarian society. It all started with the Industrial Revolution, I believe, when people were forced into cities for the benefit of the industrialist.
I, for one, will be more than happy to move to an urban/country setting, but do not have the wherewithall to do so. It's an excellent way, though, to avoid the tyranny of multiculturalism and diversity mumbo-jumbo.