The Black Death was pretty horrible and yet European society still exists.
The Black Plague is not even a cold compared to what we can engineer.
Really though I can’t imagine what you think this pedantic obsession with whether or not everyone gets blown up immediately is adding to the conversation.
We'd be 10 thousand not 10 billion and life would suck but we would survive. And the fallout would clear within a few decades or centuries.
10 000 people is not nearly enough for a modern division of labour - we'd be reverted back to prehistoric technology levels within a generation, with a bonus of fallout and absolute climate dysfunction. Given a sufficiently destructive nuclear exchange literally every single human could die.
"Societal cohesion" doesn't do too much to help us survive crop failures and wet bulb temperatures over 35C.
Aside from that, I think you might misunderstand your causal arrows a bit. It is fair more likely that massive industrialization and late state capitalism led to a society that valued the individual over the social unit, rather than that a sudden desire to be individuals sprung up in people's hearts and made a mess of the world.
All that where created by an individualistic approach. Party now and let future generations deal with the dirt.
How so? TFA attributes this modern alienation to changes in the American family structure that took place in the last half of the 20th century. All three of the threats the person you’re responding to listed, nuclear war, (modern) biological warfare, and climate change, were developed or essentially locked in in our society prior to the last half of the 20th century – largely by people born before or right around the end of the 19th century, who were presumably much more attuned to this “dutiful family obligation” mindset, since those are the very people TFA is contrasting these post-1950 changes against.
The plain history of these developments would seem to argue that post-1950 societal changes had nothing whatsoever to do with these threats, unless you’re arguing that the effect preceded the cause.
Turns out that’s a bad way to structure a society and being hyper individualistic just ends up in your society collapsing.