I doubt it because government will feel threatened considering allowing two currency to coexist and one which is not in control and decentralized could potentially hurt their economy. the uncontrollable currency is a huge disadvantage for the government considering that they need control over everything to let things run as they were planned and crypto will become a hindrance.
But it could be possible to use both fiats and cryptocurrency hand in hand, there's no pure reason why we need to transition and to convert fiats to cryptocurrency completely, as long as we all find benefits to what currency we want, it is already a good thing for us. The advantage is, we have our freedom to choose between decentralized and centralized. Both offers an effective way to transact with people, both with practical purpose and both are needed to make our economy better.