If Indian Government banned crypto-currency then you will not be able to encash your crypto-currency in INR. But you can hold your crypto-currency in your personal wallet. No Government can take your crypto-currency from your block-chain based wallet. You can hold your coin as long as you want.
As per latest news, Government of India don’t want to ban crypto-currency. They only want to regulate the Black money involved. So, they are trying to legalize it and thinking to apply some special tax in it.