Shin already spent half its run time exploring how governments operate under crisis and how global politics might react, so that's not super outlandish.

But, it also ended with the weird human bodies melting off Godzilla's tail which would almost certainly have to be explored in any sequel. Even if it doesn't have an actual Kaiju sized monster, its at least set up to run with that idea of his rampage leaving an unfinished scar across the nation they still need to heal.

Which fits right into the nuclear bomb metaphor all over again.