I live in the UK, where we've had instant, free, interbank payments for the last few years (we've had free interbank payments for > 10 years, but the instant part came in a few years ago as part of the Faster Payments scheme).
Spoiler alert: it has not eliminated the need for credit cards. The credit card system has a lot of flexibility and integrations to make for a superior user experience in a number of situations. For example, a lot of banks let you create virtual cards for specific purposes (eg: I have one for all my online subscriptions, and another for merchants I've not dealt with before). Not to mention Apple/Google Pay and their integration into basically every single online payments platform.
Spoiler alert: it has not eliminated the need for credit cards. The credit card system has a lot of flexibility and integrations to make for a superior user experience in a number of situations. For example, a lot of banks let you create virtual cards for specific purposes (eg: I have one for all my online subscriptions, and another for merchants I've not dealt with before). Not to mention Apple/Google Pay and their integration into basically every single online payments platform.