So ask yourself this:
If you're in the supermarket and want to pay your bread and butter. You have to choice to pay with your credit card (and pay the fees) or to pay with btc, dash or whatever the currency is you're holding directly.
What option will you choose? I don't think that will be the credit card.
In a world where blockchain technology has reached mass adoption - I don't think there is any real use for credit cards.
The cards themselves would merely be a gateway for mass adoption. It will be much easier in the short term to get people to use something they are familiar with - i.e. a credit card. While the crypto/blockchain aspect happens behind the scenes, it can be a tool to educate the public and bring crypto mainstream. This will help pave the way for a better crypto payment system.