The historian of civilizations Arnold Toynbee late in his life regarded the world as being one civilization. With the economic entanglement between the United States and China, that is easy to see. Certainly there are many differences culturally, yet they are not separate civilizations nor is the world economy entirely localized in developed nations.
I would disagree that the east was ever in power of anyone besides itself. From the Shang dynasty to the Chin and Han China had no dominating power over the west. The Mongols were influential and devastated Russian lands however their conquest and Empire did not encompass much of western Europe. In the 14th century a Turkic-Mongol named Tamerlane conquered much of Iraq, the Caucasus and Southern Russia. The Americas were conquered by people from its East; Europeans, in the 15th century, and never recovered though a synthetic Euro-Afro American culture developed that became indigenous itself. Muslims conquered more lands that were formerly European obviously, yet the Arabs were not too Eastern of a people.
China regaining or recovering power is occurring within a western economic philosophy, or rather two western philosophical paradigms; Marxism and Capitalism. Much of the brilliant Chinese scientific contributions are done with collaboration from westerners or even while working at for instance, American Universities. China has lots of foreign investment, though some investors have relocated production to Vietnam recently to avoid the problems of Chinese tariffs and recalcitrance at becoming fully equal economic players on a level field with western nations on issues such as protection of intellectual properties, patents and currency valuation.
World economic powers of wealth and capital are trans-national these days, unfortunately in some respects, good in others. If one region of the world were to collapse the economy would be exploited for profit and redeveloped by others to exploit cheap labor or consumers. If the population of a region were to collapse from genomic terrorism and mass die off such as the 13th century Bubonic plagiues of Europe, others would swiftly move in to fill the shoes of the departed, and the population that remained might become more fecund and replace their population within a couple of generations.
Regions of the world are no longer remote or isolated. People scour the world for investment opportunities or cheap places to live. If any part of the world were to collapse that would present an opportunity for regional reconstruction and renewal such that it would be better than it was before.
In my opinion the best prospect for collapse is simple the world population itself. The causes could be the collapse of the ecosphere’s ability to support human life stimulating a cascade of disasters such as wars, famines and plagues, or genomic terror effort gone a