What would the world be like if China led? Whatever Xi wanted it to be like. I do not want a non-democratic, dictatorial power leading the world. You might think that most of the world does not care, and maybe they don't right now. But this is, I suspect, due to the relative benevolence of historical U.S. policy of international law and order. New boss same as the old boss is a motto that is only as informative as the extent to which the new boss acts like the old boss.

Why would the world care? Take Trump's threats against Greenland...actions that run completely contrary to our historical policies and treatment of our Western allies. They were alarmed, because when the leader of the most powerful military in the world makes a threat, you have to treat it seriously. Despite Trump's hubris, such an invasion did not occur because Americans, Congress, made it very clear that Trump would be impeached if he invaded our NATO ally.

Let's say China is ascendant. It is now the dominant military and economic power in the world. China is under Xi's complete dictatorial rule. Xi decides that invading Greenland is a good idea. Stopping that internally would not involve democratic processes, it would need to involve a coup.

Let's make it even more stark. If Germany had won WWII and had become the ascendant world power, would it make a difference to most countries? ABSOLUTELY YES. If there is going to be a dominant world power, the character of that nation matters.

Are there other nations with the character and institutions that could do as well or better than the U.S. has done? Sure. I can think of several nations. But let us not pretend that all nations are equally bad/good for the world.