> As China rises to become the new gravitational center

I don't think you can just state something like that as some sort of axiom without providing any rationale. Obviously China has become much more powerful and important over the past 4 decades, but I highly doubt they will be the new "gravitational center", for two primary reasons.

First, their demographics are horrible - their population peaked 5 years ago and will continue to decline, meaning they will need to look inward to dedicate more resources to supporting their aging population. While fertility rates are well below replacement in nearly all of the developed world, the extreme ethnic homogeneity and near complete inability to assimilate immigrants long term make East Asia's demographics much more problematic.

Second, nobody wants a conformist autocratic society to be the "center of gravity" of the world. For decades following WWII, the US, despite all of its problems, really was looked up to as a beneficial force by many (yes, again, I know we did some extremely shitty things during the Cold War, but just looking at surveys of different countries' views of the US it was overwhelmingly positive in the Western world). Whereas today, despite China being essentially "the world's workshop", basically all of their trading partners look at them with suspicion and reticence.

I think we're looking at a near and mid-term future where there is basically no (or a crumbling) center of gravity. And this is basically what existed in the areas of the former Western Roman Empire for centuries after its collapse until the rise of Charlemagne, so I think your comparison to "decaying Roman Empire" phase is apropos.