Bitcoin is decentralized, and therefore we have alternatives if we decide not to use dollar, and governments will not be able to impose guardianship over us.
The dollar is involved in every meal we eat or coffee we drink. Global supply chains depend on dollar. Most fuel is priced in dollars, transportation and insurance vehicles are priced in dollars, and even countries that have begun to reduce dependence on the dollar, the dollar still represents the largest part of the budget, so replacing the dollar is currently impossible.
You're right but in a world that's dependent on fiat currency, bitcoin alone isn't going to cut it. You'll have a hard time being able to use bitcoin when the world doesn't fully adopt to it. I wouldn't say impossible to replace the dollar though, there's got to be a tipping point for the dollar and the US government that it's going to be a hard time for them to recover if the breaking point for them is finally reached but as you've already pointed out, the influence that dollar have on our global economy is just too big and deep rooted that it would be difficult to get them out without creating some damages.