I see your point, but I’d still argue that maybe we can think of the nuclear threat and the cold war as different, but related things. It was less the physical threat of nuclear annihilation that underpinned it, and more the tensions between the two that defined it - maybe that’s because of my own position as a cultural cold war historian? I’d argue that if we had had Roosevelt finish up the Cold War instead of Truman, things might have gone differently. FDR had already shown Stalin that he was willing to work with him, and Truman came right out of the gate antagonistically. I think the tension was separate from the nuclear threat, but that just amped the feeling of the threat and probably really restrained actions, except in terms of proxy wars.
As for some super power getting them… I think we might be too economically interconnected for that sort of thing to work the same way. The real or perceived nuclear threat seems more localized - in the Indian Subcontinent, with North Korea, in the Mid. East, with an undeclared arsenal in Israel and Iran looking to maybe make their own (other countries, too, we just don’t talk about those). That doesn’t mean it couldn’t happen, but right now, I don’t see it as an organizing principle of global politics. The economy is, and the crisis in the middle east is. Those actors are, again, very local and regionalized compared to the Cold War era.