Can you substantiate this claim?
... that non-ICBM nuclear weapons would be 'nearly as destructive' to the user as to the enemy, of geographically adjacent nations?
India has roughly 80-100 weapons. India has been focusing on low-yield devices (with most apparently falling in the half-kiloton range.) Given how nuclear fallout works and the like... India and Pakistan launching their arsenals at one another would result in a large contaminated area affecting both nations.
Now, if you're talking about the effectiveness of MAD deterrence ... if MAD was ineffective the world would have glowed in the dark after the Cuban Missile Crisis.
Last month I was involved in a conversation thread about what the impact of a hypothetical nuclear war would be on existential risk.
There are many potential nuclear war scenarios which would have varying impacts on existential risk. It's difficult to know where to start to gain an understanding of the long-term of nuclear proliferation.
For concreteness, consider the case of an India-Pakistan nuclear war.
According to Local Nuclear War, Global Suffering by Robock and Toon,
[...]
Note that this would presumably cause some degree of chaos in the developed world.
I have not yet investigated the credibility of the papers' claims. However,
Suppose that an all-out nuclear war between India and Pakistan were to occur and were to result in climate change killing 1 billion people. Then would the probability of a positive singularity increase or decrease and if so why?
This question seems very difficult to answer; maybe altogether too difficult for humans to answer. I welcome responses raising relevant considerations even in absence of a good way to compare the relevant considerations. Please read the linked conversation thread before commentating.