From first hand experience - one of the main problems toward any significant growth in e-commerce/e-interactions in India is the lack of reliable visa-mastercard framework, e-anything/e-payments do not exist. Facebook can make a bigger dent if they can find an easy way to get people to spend money online - for people who are wary of online transactions. In that sense I think Amazon would be a bigger winner in this tech war if they decide to enter the Indian market