Isn't the EU the world's largest economy at present? Anyhow, one of the issues I see that will face both China and India is that their starting or boundary conditions are governed by such huge populations at the outset. The US, and to an extent European nations, have rejoiced in the benefits of being able to increase population in parallel with economic strength. Neither China nor India have room to do this. On the up side, they both have vast labour markets. But as we are seeing in both India and China at present the potential for civil unrest as a result of the immense offset in wealth between the developing minority city dwellers and the majority urban population is very real.
It will be very interested to see how both countries handle aspects of distributing wealth and the growing need to develop rural areas.
EU might be the largest economy but I was referring to individual nations.
Yes, population is one of the major problems but it can be used in a positive way. India and China produce a large number of graduates each year. Both the countries have a large number of skilled as well as un-skilled labour. So, opportunities like outsourcing can be a great boon for both India and China. Utilization of other resources can also be beneficial.