For the case of bitcoin I agree with what you say because since the beginning bitcoin was not created to run the economy of a country but bitcoin was created as a system with decentralization to get us out of government control or bank systems that have existed since the beginning.
Indeed, government would never let this scenario happen. They would never allow a currency they do not control to become the main unit of account in the economy.
But talking about the dollar now they do have great power even though the dollar is now weakened but they still have a dominant role because they still control about 50% more global foreign exchange reserves. This indicates that the dominance of the dollar is still very pronounced today.
https://cepr.org/voxeu/columns/dollars-status-through-lens-foreign-exchange-reservesIn addition, petrodollars are also still one of the factors that is quite logical to say that their dominance is still very large now even though there are currently some complicated situations especially when discussing geopolitics but it cannot be denied that currently petrodollars are still one of the things that every country will not be able to let go of.
As for the usd and petrodollar, they still dominate the global economy, but dedollarization is no longer just an idea. It's already happening.
Years ago, usd accounted for more than 71% of global foreign exchange reserves, but that share has now fallen to around 50%, as you mentioned, and it could continue to decline in the future.
Likewise, Iran has used the yuan through CIPS, instead of usd and SWIFT. Saudi Arabia has also signed agreement with China to use the yuan instead of the usd. And within BRICS, an increasing number of trade transaction are being settled without using the usd.
https://americanalternativeassets.com/blog/predicting-the-future-of-the-dollar-in-a-changing-world/