What do you think? Will cryptocurrencies eliminate the need for credit/debit cards in the future? If not, why? Your input will be greatly appreciated. Thank you very much.

The first step of doing this is that cryptocurrency can be accepted as a currency, as the pay method and accepted in most countries worldwide. Without this, this will mean that more things will be hard to do.
ANd so far, accepting cryptocurrency as a payment method is still illegal and not accepted in most countries. So, the answer is:
this will be very difficult, moreover the term of
"eliminating", seems like impossible.