You are unaware it means that few countries had long back only have banned cryptocurrenices in their country and recently too some strict actions has being taken like banning ICO, trading in few countries. So you stating that it can never be ban is absolutely wrong.
If India bans bitcoin, that does not mean that the users will stop trading altogether and they wont be able to trade their coins, the best thing they can do is to ban the exchanges running inside India , bitcoin is a global market and you can trade anywhere in the world and make arrangements to reach your money to your personal accounts.