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.
Well, in this case, what you say is right, although for El Salvador things may be more different, because with support from the government it is possible that credit cards still exist but that credit cards based on BTC are with much more benefits, and I think that those countries and banks that support something like this could be very successful.
The traditional economy is still very booming, since it is clear the control that the governments have as well as the banks, banking has been a total success to maintain people's debts and I think that with the debt they have gained a lot, so it is difficult to undo a business model of many years.