Most of what you have talked about are just assumptions that you made @OP,
You also have little to ZERO idea about each nation's population and military capability.
Each country has their own military power that you know fully until there is a crisis that demands it. Forget the numbers and what it is reported on the internet about the power, size and strength of the military of some countries, some countries will surprise you with how strong their military is in size and tactics when they are at war. The military pf every country has been developing over the years and is not what it was yesterday that people know.
I started to become addicted to wars and world history when I was 10 years old. So I started and wanted to read all the wars and conflicts and history and geography of course to better understand the backgrounds from different sources to avoid bias and come up with better imagination. And it would be the dumbest idea to ignore the various statistics reported unless you have better knowledge to start your estimates than those groups and organizations which actually consist of experts, researchers, agents, etc. Obviously, they are not accurate but they are a good basis to start estimating their numbers and capabilities.
The nukes will be the real equalizers when it comes to total war and nobody will want to start a nuclear war unless it is out of desperation or when some of these superpowers are already depleted.