I wonder when China will pass the USA.
You should be asking "if" rather than "when". All throughout the 80's people were anticipating that Japan would eventually pass the USA. Obviously that didn't happen.
There is more to economics than just follow two regression curves and seeing where they intersect. China has deeper issues that the US doesn't have. For example, entrepreneurship, and the associated creativity and risk taking, is valued much more in the US than in China. That is one of several factors working against China. On the other hand China has a lot of people and may pull ahead just playing "catch up" and getting per capita incomes to a decent level (though still below US, Japan, Western Europe, etc...). It will be interesting to see how it actually turns out.