We are not talking about real estate prices but Gross Domestic Product, i.e., the value of all goods and services produced.
In real physical terms measured by PPP, China economy is about half of America and growing fast. Also having larger population accustomed to lower standard of living might make you stronger (as it did with Soviet Russia versus Germany).
I have no idea what PPP is, but there is no way on God's green earth that China's economy is about half of ours. Your second line about "a larger population accustomed to a lower standard of living might make you stronger" is lunacy. If Germany did not have a two front war, it would have defeated the Russians without too much of a problem. It was the allies providing the Soviets with food and munitions that enabled them to resist the German onslaught.
Purchasing-power parity (2003):
European Union 10,840 28,600 379
1. USA 10,400 37,600 290
2. China (mainland) 5,700 4,400 1,287
3. Japan 3,550 28,000 127
4. India 2,660 2,540 1,049
5. Germany 2,180 26,600 82
6. France 1,540 25,700 60
7. Britain 1,520 25,300 60
8. Italy 1,440 25,000 57
9. Russia 1,350 9,300 144
[...]
(World Countries by Gross National Product)