In the long run present day nominal GDP doesn't matter. For example, after world war I Germany had a very bad economic situation. Land, natural resources and culture matter. Russia is the largest country on Earth. China is the largest population and largest economy. India is a close second. The fact is Eurasia does not need the North Atlantic Empire.

Time will tell but much of the vaunted "Western" prosperity is a fading high from the now 70 year old post war era. It is not inevitable that America leads forever.

I wouldn't be too cocksure.

Also, things like population trends or nominal GDP are very changeable over the course of short decades. What matters is resources, land and will and unity of purpose.