What does personal information about a person stating his opinion has to do with the stated view? Nothing. Lets not go to ad hominem comments.
A nifty calculator where one puts in growth and it draws up graphs:
(updated for 2017 actual GDP)
US GDP growth in the last 10 years (one has to choose the 10Y option)
Same for China
Comparable trends for countries turning from low income to high income economies
My prediction that it is likely Chinese GDP in nominal terms will overshoot US in the 2040 to 2049 timeframe stems from the graphs above. Without ANY US meddling and tries to pressure Chinese economy, the average GDP growths for the next 10 years work out at 2.3% for US and 5.6% for China. The overshoot year in that case would be 2033. But from 2029 to 2039 one would have to correct the GDP growth rates again. And while US may indeed be lower than 2.3%, the past graphs of SK/JPN/TW suggest any country will inevitably slide further. Possibly to 4-5% for most of that period. Adding a few more years to that 2033 prediction. And then when one DOES include efforts by US and other countries allied to US to pressure the Chinese economy, the year 2040 seems quite reasonable to me. I again stress, to me. This is a personal line of thought. One can disagree or agree but there's little reason to discuss one's personal thoughts in detail. And depending on the exact nature of the outside pressure on Chinese economy, it may not even be 2040 but several years or a decade later.
Of course, none of that is precise. There are variables that can't be easily predicted. Currency exchange rates influence GDP sums greatly. But there is no significant historical precedent that i see suggesting Yuan will drop under 6 for a dollar without impacting own economy.
Inflation rates can influence GDP growth too, though they seem similar.
and
, with both being around 2% on average for the last 10 or so years.
Past performance is no guarantee of future performance, of course, but aside from using other countries in similar situations (none for US, barely some half-applicable countries for China) there is literally nothing left to base a prediction on. Sure, a meteor can strike US or China. A disease may wipe out 10% of the population. Various economic bubbles can happen, etc. But none of those can be predicted with any certainty. So in my opinion they're better left out of any predictions.
In any case, likelihood of China going past US in nominal GDP in 2020s is, in my personal opinion, under 5%. Likelihood of it doing the same in 2030s is perhaps 30% or so. And likelihood of China doing it in 2040s is 50% or so. With remaining 15% being for 2050s, 2060s, or any other later date. These percentages are mostly taken out of thin air, based a bit on the data above, but also trying to take the more unpredictable events like burst economic bubbles into consideration.