I dont think we'll see the same type of dominance as the US currently holds. US is basically an anomaly when you look at it. From its geographical position (protected by two oceans, insane diversity of nature/climate in the huge mainland, with all kinds of natural ressource at home), history (born out of genocide and slavery, meaning free land and free labor to build the economy on), the fact that it was born out of OTHER empires (UK, France, Spain), that it has cultural ties with the center of the Old World (Europe), extremely diverse population. In a strange way the US is still a fairly young country while being very old when you go back at where its main population comes from and the traditions that birthed it. It's basically the end result, the magnum opus of colonization. And it literally has interests and its hand in in damn near everything everywhere. All that to say that if/when the US collapse, which isn't a sure thing, most probably you'll go through a periode of high instability in the world (not seen in modern times imo) and then we'll revert to the norm, which is a world with various old historical regional superpowers (Russia, China, India, France, Germany...) plus a couple of new ones maybe, but no global "hyperpower" like the US. I don't think another country could enjoy that sort of dominance, especially culturally.
