USA was the most powerful nation at one point, and we did a good job of running the entire world into an almost global recession. Maybe it's time for China to step up. China becoming the most powerful country in the world isn't hard to imagine. They seem to surpass the USA in educational standards and environmental policy. I don't think anyone is considering the positive possibilities.
They would eventually try to conquer the world. Sure, the U.S. is not that great of a nation, but at least this country will protect my freedoms. China wouldn't care about your freedoms. As much as we like to think China is an ally, we forget that it has a Communist government. And we know from history that usually leads to world domination. It would just do the same thing the U.S.S.R. Did after WWII and form satellite nations. And they will keep it up until the free world is all but gone. In order to do this they will probably ignite World War III, and we all don't want that.
China is currently better than the United States in many sectors, and if their progress is linear, they will overcome the United States in environmental regulations and education and productivity. Human rights and censorship are obvious points of contention, but nothing can overcome the power of information and its dissemination. Nin hao overlords.
It is not a good idea to have the source of power owned and monopolized by one country, alone. There should be several strong countries to share the provision of power amongst the less developed countries, such as Germany, USA, China, Russia and Brazil. They should also be selected to provide power, even installed by China, but run and owned by a group of strong countries.
They could impose all kinds of restrictions. They could cut our power off if there was a conflict. They would have control over our lives by having control of our power. They would control the whole world by controlling the power. That would turn us from a free country to a controlled country.
China has many positive attributes, but its government is not one of them. If China, under its current regime, becomes the main world power, then the planet will suffer. Whereas, the U.S. and European powers take great care to promote responsible government and development around the world, China's government is more concerned with its own needs and, as a dictatorship, certainly does not care about the spread of democracy or human rights in the world.