I once visited the VI store, and i have to say that they are working well to keep their customer base intact. The only thing that is required is that the sound quality over voice calls, and data services should be improved.
But, i suppose, this requires investment from foreign establishments which Vodafone-Idea is linked with. It might though have restrictions from Indian Government. But, if that does happen, Jio and Airtel will have a good competition.