If we fall as a nation, just under 7.6B other people get a shot at running the show and fix what's broken to whatever extent we can. Good for them, bad for us.
I can't see any other nation becoming the world superpower any time soon with the exception of China. The US is unique in that it has a trifecta of components necessary to maintain its power. It has the natural resources, it still has a great talent pool and one thing it seems to have over everyone else is a level of net immigration that allows it to mask the population implosion that is happening in all other western nations and China. China may very well surpass the US or at the very least rival them but I just don't see how they are going to overcome the population implosion that is coming for them in a few decades.
A loose confederation of 1.8 billion Muslims or approximately 1.4 billion Indians might have a thing or two to say here in the long run. It's not all about China and the US. Even more so as they both pursue policies leading to their own irrelevance in that same long run. But also; "Prediction is hard, especially about the future." - Niehls Bohr
Well none of us will know what happens in the long run. Maybe climate change will wipe most of us out? Best we can guess is short term (next few decades). That time frame is where my comment was really aimed at.
The next few decades will determine the impact of climate change. It doesn't seem like a particularly hard problem to solve: embrace solar and nuclear power ASAP globally, but nothing is easy when people get involved. But even China seems to have read the memo now. But also, if someone even blurts out "clean coal" point and laugh.
Seems like Chairman Xi is serious about tackling Climate Change so he does not get deposed if the Gobi desert grows and eventually swallows up half of China.