TLDR: China and the Global South are dramatically improving their research quality and quantity, while US research is falling behind because private companies don't want to fund it and the education required to do it.
As the Global South develops to match/exceed the West, I expect countries' research outputs to be near-proportional to their population sizes. China has yet more room to grow to 4x the US's research output to match their population.
It will be an incredible day when China and India make 4x as much research as the US, while Indonesia matches or exceeds the US. If the Global South can form larger collaborative research blocks, we could see country blocks outcompeting the US in research on every level.