You're making lots of questionable assumptions here. Primarily one being that the US (and indeed the EU) continue to exist in their current form on a 20 year ti

You're making lots of questionable assumptions here. Primarily one being that the US (and indeed the EU) continue to exist in their current form on a 20 year timeline. Given the political climate in both, that seems unlikely. Given that the US is reindustrialising [https://doc-research.org/2018/06/reindustrialisation-us-deglobalisation-china/ https://doc-research.org/2018/06/reindustrialisation-us-degl...] right now, it's extremely unlikely we'll see a decline in German manufacturing - even if that means an increase in european protectionism. There's no way Germany (who hold vastly outsized power within the European Commission, especially in a post Brexit world) would willingly allow that strategic and economic advantage to wilt. Especially given the economic decline and social disintegration that the move to a service economy wrought on France and the UK. Chinese economic might is almost entirely based on exports, in an era of increasing protectionism and at a time when their manufacturing base is moving to places like Vietnam and to a lesser extent India. The US's failure to invest in infrastructure (everything from broadband to roads to dams) has left it in need of massive capital investment. And of course massive internal investment (arguably unsustainable and fraudulent) in construction. I'm not suggesting these are paper tigers, but neither are assured of 'superpower' status. Moreover - the enormous material costs we're starting to see from climate change will accelerate. We can estimate some impacts, such as enormously larger migrant crises and water wars. But the second order effects of this are extremely unpredictable.