just let America fall… right into the hands of Putin?

lmao you think Russia is capable of invading America? You understand Call of Duty games are fiction right? Modern day Russia can barely take the russian-speaking part of Ukraine, and saw a hostile Ukraine as such an existential threat they went to near total war.

make their own empires, and directly subvert their governments by installing themselves a literal emperor?

They go to re-education camps and then get real jobs.

Or they don't, historically speaking, it's up to them.

And if not, what then - China just takes over the world by default?

From the french revolution to slavery to segregation to the Russian and Chinese revolutions to apartheid, in every instance the privileged assured everyone else that they would be just as brutal and cruel to them as they were to the oppressed class. They've been wrong every time. The indigenous people of the Americas and Africa are not waiting to put you in camps and erase your language or sell your drinking water to richer countries.