Well that was a very boring read,so pardon me I am responding without reading that
One simple theory I believe that with rising GDP it will become hard for any nation for maintain a constant growth,I mean for China growing at 10 % will not be easy at $ 10 trillion as it was on $ 6 trillion.
Meanwhile a country with smaller GDP can grow at a faster pace due to its small economy.
If India overtook China in growth rate does not mean that India is growing faster than China,because even a 7 % of 10 trillion will be greater than 10 % of 5 trillion,just my opinion.