Bitcoin will never replace the dollar, but it can become a real currency with at least something secured, unlike all other currencies. After all, they (currencies) are issued by central banks and even private banks (as in the USA) for their national purposes. Bitcoin is untied from national borders, so in the future it will keep the dollar company on the financial "Olympus" - this is obvious to many today.
Bitcoin is not designed to replace the dollar or any other currency. Theoretically, dollar is backed by gold , it means it represents a value.
El Salvador recently announced the recognition for bitcoin as official currency. The crypto community is actually waiting for the next countries who follow it. The president of El Salvador said that 2 countries will adopt bitcoin during 2022 , while other hope for more countries. This brought more hope for many of us that dollar can fully replace dollar. I think it's not just a matter of large adoption as there still other obstacles that need to be solved .