To the extent that US practice impoverishes it's own people, it is in decline. The more wealth is concentrated, the more rigidly maintained those mechanisms for concentration, the less the nation as represented by it people can be great. That seems to be the way it works in America.
But if "the west" had its origin in the Ancient Greeks, stories of decline are nativist entertainment. Even talk of hegemons is misguided.
Science isn't uniquely western, but I do think the eastern approach is destructive of scientific knowledge. Which, by the way, means China IS Darth Vader. "Don’t be too proud of this technological terror you’ve constructed. The ability to destroy a planet is insignificant next to the power of the [East]."
That technological terror, though, that's what enabled all those people in poverty in China to be "lifted" to less absolute a poverty. China did it. With the tools of global interconnectedness.
I don't think China can sustain as productive, and terrible, an empire as the US and the Europeans have done. For better or worse, we'll be poorer, and dumber, and saddled with duller entertainment, under the Chinese thumb. It'd actually be bizarre if somehow western crisis collectivism somehow didn't respond to being so bored.
That's probably one of the stronger reasons China keeps trying to separate western powers. Don't trust the US, don't be led by others, you're in decline, know your place. It's telling just how miserable the Chinese approach to other powers is.
The "decline" of the US is the "rise" of China inasmuch as the condition described by US "decline" is kind of an ideal world. That "rise" isn't a rise to prominence of glorious, what achievement? It's a settling at a lower level.
Papermaking, printing, gunpowder and the compass. Anything else over "5000" years? What were the social and cultural achievements? Pottery?
Seriously, why is it going to be a better world for most people?