Things to criticize:
1. Great profits in the past by investing in gold doesn't indicate that the same investment strategy will work in future.
2. Predictions are risky. Though emerging economies may have a great chance to perform well in years to come, their economies may also fail due to unpredictable factors, such as natural disasters, social unrests, etc.
3. It's hard to say Gold will be the BEST investment, because there are so many other good investments, such as stocks, foreign currencies, etc.
4. In fact, as investment history has suggested, investment in gold can be very risky, and the price flucturations could be big. A sensible strategy has always been to spead out the risk by building an investment portofolio.