Then we can plot the trend curve and say that China' GDP would surpass country X's by year 2xxx.
This is not likely to happen. We are all heading for really tough economic times, which China also made its share of contribution to, by consuming huge amount of commodities, and jacking up their price.
China should be tested on how well it can survive tough time. Then we can make better prediction on future growth potential of China. So far we have seen its performance under really favorable condition and gave it too much credit than it may deserve.
Tough economic times now would be a political disaster, and lead to widespread social unrest, which is what the central government is desperately trying to avoid.
The Asian meltdown of 1997 hurt them much more severly than us. The social ramifications were at least as significant.
The west can live with $140 oil. The Chi Coms can't.
They don't sell us much we really need. They need commodities.