Do firms want Mandarin speakers? Will they need Mandarin speakers 3 - 5 years from now? Will I benefit from learning Mandarin? I already know English and Hindi.

I think that being multilingual, you will have a much greater chance of getting hired by a Big Four Accounting firm, such as KPMG, or the other three. I work at KPMG, and there are many people here that speak multiple languages. In the ever-growing international marketplace, there is always a need for people who can speak more than one language. The more you can speak the better. Chinese is especially good because of all the business growth that is currently taking place in China.