> Austria? Brazil? Indonesia? None of those are nuclear-armed states

This is a little bit moving the goal post, I was only arguing against your point that this treaty was just a bunch of plebs signing a petition. But I would just like to point out that South Africa is a previous nuclear state which is a party to this treaty. Disarmament has precedence.

History has examples of nuclear states cooperating. 6 of 9 nuclear states have signed the Comprehensive Nuclear-Test-Ban Treaty (China, France, Israel, Russia, UK, and USA) and 3 have ratified both annexes (France, Russia, and the UK). No signatory (including the USA) has conducted a nuclear test since 1997 and North Korea is the only country to conduct a test since 1998. This treaty has been a huge success even though we can still do better with respects to North Korea.

The Non-proloferation treaty is an even greater success. India, North Korea and Pakistan are the only nuclear states which haven’t ratified it. Since it came into effect in 1970 we’ve seen the worldwide stockpile decrease by more then half. But we can still do better.

At the risk of muddying this post with unnecessary geopolitics I’m gonna be equally speculative and come up with made up scenario which counters yours. The point of this exercise is not to make predictions—as they will probably not come true—but to demonstrate that fictional scenarios can back up either cause. You did yours, so here is mine:

* During this decade more and more countries will sign and become parties to the Treaty on the Prohibition of Nuclear Weapons. At some point a NATO member will become a signatory (perhaps Germany or Norway from popular demand and favorable government; or Turkiye to assert their independence).

* At some point, seeing the world take the cause of total elimination, the UK might become the first nuclear country to sign the treaty. Perhaps after a Labour victory during a push from party members which oppose the nuclear weapons program.

* With most of Europe having signed the EU might pressure France into signing.

* Israel might go the way of South Africa, with a post apartheid government dismantling the program on their own volition.

* India and Pakistan might have an easing of relation and as a sign of good will they might sign this treaty jointly.

* Korea might unify, and the unified government might want to put it’s dark past behind it with a strong sign of cooperation.

* After most of the world has signed China might fear the optics and might sign in the hope to prove it’s moral superiority over the USA. But secretly sees their program as expensive and unrealistic so this treaty—if proven popular—might be a good excuse out.

* Russia might follow Europe if tensions around Ukraine ease and sign the treaty from popular demand both domestic and from other countries. Or it might cop out for similar reasons as China in this hypothetical scenario.

* This leaves only the USA. Maybe in a decade or two—if this treaty proves popular—and only the USA and a few microstates which depend on aid from the USA haven’t signed it. And maybe the democratic leadership shifts towards more progressive candidates which takes issues with the American exceptionalism which the current Democratic and the Republican parties share. Maybe then the USA will become the last nuclear state to sign.

Again don’t take this as a prediction, this won’t be this easy. This is only an exercise in speculation. My point is only to counter a hypothetical scenario which favors one outcome with another equally fictional that favors the other. My main point is that international treaties have proven effective in the past, and there is no reason to think they won’t this time.