Few points I can think of, if all credit cards become credit only products then main differentiator could be interest free period, like giving due date after 90 days.
Another would be to charge different annual fees from different customers, one who opts for only virtual card will have fee of ₹250 and one who opts for physical card will have fee of ₹500.
* All these values mentioned are for demo.
We all know that this is too extreme case.