Will China's GDP be greater than the USA's and Europe's combined? A newspaper said in 2080 China can be a developed country, with a bigger population. Does that mean China's GDP is going to be bigger than the USA's and Europe's combined?

Also, is this possible even though China's land area per person is smaller?
Of course this is is possible. China is a very large economy currently and it is likely quite a way away from reaching its production frontier. It has lots of room to grow.

A lot can happen in 65 years and any forecasting this far into the future will be subject to a high degree of error. Don't forget that the US and Europe are dynamic as well. The current world economic climate may be in China's favour now but in 65 years who knows. Maybe everything we will need can be 3D printed an large scale manufacturing won't exist.

It is hard to look at The Next 100 years. It attempts to speculate on what can happen. *Spoiler*, the author does not expect the 21st century to be China's.