If your cities immediately turn into "tribal warzones" when they lose utilities, you've definitely made some governance failures well before the cyberattack.
Can you be more specific? What governance processes counteract or prevent that failure?
Reduce wealth inequality through industrial and fiscal policy, don't stuff cities full of millions of culturally distant immigrants (distant from both each other and the existing population), encourage integration and patriotism instead of ethnic sectarianism via education and cultural pressure.
The 1860's are calling and the Irish would like a word. Are you arguing the Irish shouldn't have been allowed in the U.S.? Or that Americans should have been somehow coerced into accepting them? You think the Irish didn't want to be assimilated or you think Americans didn't want to assimilate them?
The 1860s when the Irish in NYC refused to fight for their new country, killing over 100 people and ethnically cleansing most of Manhattan? Or a few years later when two different subgroups of Irish killed another 100 of each other in the same city? These questions re-litigating history are immaterial to the fact that there is always some point at which putting groups next to each other will cause conflict, modulated by things like population density, culture, religion, tribalism vs. individualism, prosperity, etc.
This is just willful, boastful, ignorance, across the board. There are more examples of human cooperation, and there's more evidence that immigration and multiculturalism leads to long term stability, not the opposite. Next, you're going to tell me how the American Civil War had to do with immigration. Relitigating history is not indicated, but for starters you have to know some history.
That's funny, how do you link multiculturalism to a breakdown of society? If anything you want lots of strong societies overlapping so that everyone can find a group that can support them and each other. The "mosaic" concept has worked out fairly well for Canada, and I just can't get behind denying people their communities.
Even governance in the absence of utility can't stop human nature.