There’s another type of story that seemingly just doesn’t appear in the conventional World War III niche (as far as I can tell): Stories centered around those with neither political or military capability. And by that I don’t mean the opponents in later Tom Clancy novels. The poor innocents caught up in the heat of war are often used in historical wartime fiction, but seem at best only in parts of conventional Fuldapocalypses (ie, Bannon’s wife in Team Yankee).
I think the biggest reason is well, no real incentive to do so. I don’t really have the best knowledge, but I can speculate that historical fiction writers don’t need to use an inherently contrived “Cold War hot but not that hot” setup to tell such a story. There’s plenty of historical conflicts that readers will understand better, and if a fictional one is needed/wanted, making it small, contemporary, or both can offer more of a hook.
So it’s a catch-22. The subgenre would benefit immensely from outsiders bringing their perspective. But most outsiders, even cheap thriller writers, don’t have much motive to write such a thing.