I'm afraid that a few years is not enough. It takes 10-15 years for crypto currency to become common thing when you are paying in a store for example. Most people older 50 will never be able to use crypto currency, it's too difficult to understand for.
It is difficult to predict, because may be even 10-15 years will be not enough for it. There are still a lot of people, who dont know much about credit cards so using crypto may be almost impossible for them.