I don’t know how you made the leap from “digital currencies will exist” to “non-digital currencies will cease to exist.” Even if that were to happen, you could

I don’t know how you made the leap from “digital currencies will exist” to “non-digital currencies will cease to exist.” Even if that were to happen, you could still get paid under the table will gold, gemstones, bushels of corn, pallets of durable goods, etc. meatspace won’t simply end when a central bank issues a digital currency.