As far as I know if the RBI has banned cryptocurrency because it does not have an existing legal framework and the RBI states that cryptocurrency cannot be recognized as a legal currency and a legitimate payment system.
They removed types of bank note from the economy even and with no notice to holders, so a pretty strict regime to live under. The RBIseeks to include more of the cash economy in government revenues and unite a divided country of epic size. Some of that will be productive but also they are in danger of generating too much paperwork to conduct business instead of reducing barriers between different parts of the country.
The reason we can expect quite harsh treatment of any alternatives to Indias rupee is that the country is running a deficit in its budgeting and needs to raise amount of tax taken.