I think this puts it fairly sensibly, and I agree that we're in much the same boat regarding mutual coexistence. As much as I think it would be kind of funny to see a unipolarity-induced China implosion, I daresay it would probably be for the best if our nations are both healthy and prosperous lol.
Completely agreed. History shows us that unipolarity, supremacism (of any kind), hubris, and complacency ALWAYS comes before the fall, without fail. It's basically a universal principle now. The US getting its act together and focusing on building up instead of tearing down would also help keep China sharp and on its toes, but I see absolutely zero evidence that this "political self-reflection" will happen. The country is decaying internally and actively corrupting itself in almost every way, shooting itself in the feet at literally every single given opportunity, and proving completely and absolutely untrustworthy at the diplomatic level. It always plays spoiler and is incapable of being an honest broker or negotiator. We're also just going back to Cold War, but v2.0.
Ideally, the relative decline that has already been happening will continue gently over a generation or two, but all signs point to "little by little, then all at once". In many ways, the decline has even been absolute rather than relative. The tent cities, mass shootings, drug epidemic, fall in life expectancy, almost daily train derailments, seasonal/weather-triggered brownouts/blackouts in some states, fall in public safety, dysfunctional healthcare system, failing education system (mostly but not entirely outside of top tier institutions), inspire no confidence.
My hope is the decline can be managed very gently for another 30 years, but I do not see any evidence that it is likely. The political class seems committed to thrashing and convulsing, violently and repulsively.
On another note, I highly recommend you read work by Dr. Lyle Goldstein. He is also in your field and offered really rational and sober analysis back when he was teaching at the Naval War College. In fact, his rationality is the reason why he felt forced out.