I agree with your sentiments, except where it concerns the USA.
Why?
In the next 45 years, the USA will grow its population by between 110-170M, placing it somewhere between 420M and 500M by 2050. That amounts to a growing population, growing economic demand, influence, etc.
Another global powerhouse over the next 20+ years will be India (primarily at the expense of China).
China's internal issues also extend to internal dissent, de-stablisation and cultural and structural issues.