The major reason for Mumbai ever becoming the commercial capital of India was the harbor and the trading castes from nearby regions (Gujjus, Parsis). What has happened now is that both those assets are fast losing their meaning. Air cargo is faster and as good as sea cargo. And business skills are no longer limited to calculating and deceptive methods of the trading communities, but require more foresight and ethics (the major success story that serves as example is that of Narayan Murthy). As a result, the factors that have become more important in determining the economic competency of a region/ city are the infrastructure, quality of life, cosmopolitanism, and code of conduct. Delhi/Noida/Gurgaon definitely scores more than any other Indian metro area is these aspects. That is why NCR is increasingly becoming economically important. However, it is untrue to say that it has already overturned Mumbai's status. Mumbai still enjoys the inherited advantage of rich tycoons and big names. However, if Mumbai does not improve itself soon, even those would be forced to move elsewhere. BTW, it is not the immigrant population that is to blame for the deplorable situation of Mumbai. In fact, Mumbai wouldn't be Mumbai if it was not for the immigrants.
