It's already happening if we will talk about virtual payments using fiat and crypto. It will take time until crypto will be accepted in any means but for sure it will happen. Basically I don't think it will replace fiats as this is like the roots for using in payments.
It is quite new to the world. People are considering it a joke just because of its nonexistence physically. They think they will be getting big losses if they trust it as it can be vanished any time. Definitely this is a state that needs much bigger considerations and reservations, so coping up with all things is hard. But still we are quite hopeful for seeing a big pool of acceptance from all other countries.