> I use the term because I see NO factual basis for assuming that humankind is going extinct. Your post did not change my view on that:

There is a huge difference between I do NOT want to see, and there is NO factual basis.

From https://worldpopulationreview.com/world-cities only 1170 cities have population of 2,179,929,822, RS-28 Sarmat yield is 10 heavy warheads, each yield of 1.5Mt. Currently there is 3,700 nukes deployed and 13,132 nukes total. We do not know what China has so those number are without it. With the new hyper-sonic weapons time to react and go to shelter which in London practically does not exist except underground transport, so to get to nearest station you would need 30 min but nuke needs 15 min to arrive. Let's suppose that one Sarmat is enough to level town size of London or Paris. So only with firstly deployed there would be 2200 nukes to spare.
But what about heavier nukes those 10Mt yields, what about revamping Tsar Bomba with 50Mt (8km fireball, 68 km mushroom cloud and shock waves circling Earth 3 times). So, what exactly will intercept hyper-sonic? So when you say estimate 1.6 to 3bn I would rather say it is very optimistic, and that only from the blasts. Next goes fallout... are you saying no one will die out cancer in full exchange? It will be all ok after 5 years?
EMP would wiped out grid and internet, what will exactly pump water? What are you going to drink? Quickly made filter from charcoal and that will do?
And to what hospital are you going to go if you scratch on rusty nail for instance?
Next, what are you going to eat, 80% of food in UK is imported, https://www.businessinsider.com/no-deal-brexit-percentage-br... there is no more ships with food and oil?
Where are you going to get money banks are out, no plastic cards, cash does not worth anything? do you have silver or gold? How many will die out of hunger in next 10 years?

And what about nuclear power plants 450 of them? They are not the same like nukes, nukes burn their fission material, but as we know from Fukushima Daiichi Accident and Chernobyl disaster, they were quite tricky, and there we managed to do something about it. Who will go to "fix" nuclear power planets after exchange, so plenty of fallout there?

As I said it would not be extinction but 99% reduction, and those who survive would wish they have not. By the way I am not trying to convince anyone people have had too many video survival games with happy ending, and to test reality you just need to go to near by woods for 7 days without food and water, and what ever experience you have just multiply by 300 times.

Going back to first line,

> your post did not change my view

I somehow find more frighting and delusional that way of thinking, as it leaves possibility to use mentioned as solution for fixing problem as people optimistically believe they are the one that will survive.

There is a reason why "Mutually assured destruction" and "nuclear deterrence" exist as such, as no one will ever attempt any such idiotic thing. As what we model usually does not correspond with reality. And when you know that everyone will loose like in the move "War games" then only way to win is not to play a game. And if current narrow AI can do it today I hope you as far superior intelligence can come to the same conclusion.