Mumbai dying?

The Hindustan Times Brunch had an interesting article, comparing Mumbai, Delhi and Calcutta.

The article suggests that while the 19th century belonged to Calcutta and the 20th to Bombay, the 21st century belongs to Delhi.

Do you think this is true? Is Mumbai on a downward slide? Does the 21st century belong to Delhi?

I summarised the article here; would love to hear comments: Delhi - 21st century city?