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This is true, one clear example of this is Zimbabwe, after the disaster their fiat currency became and after other foreign currencies became the money people used on their everyday transactions the government tried to impose once again their currency causing yet another crisis, so even if bitcoin and other cryptocurrencies could deliver a knockout blow to fiat currencies and destroyed them in the process governments will at a later time try to reintroduce their fiat currencies as a great deal of their power derives from them.
I am not following the Zimbabwe economic crisis and i have not heard about them enforcing others to use their currency once again. When i check about the worst ten economies in the world i did not see Zimbabwe. Iran comes first along with Vietnamese Dong. Suppose even if the government enforces will the people change their methods and start accepting their currency or look for a stable one.
The link to the Wikipedia mentions what I am saying, the hyperinflation that we saw in Zimbabwe was probably the worst in recorded history, then the government had no other option but to give up and get out of the business of printing their own currency, only to try to do so again creating another crisis and inflation being above 700% per year, while the government of Zimbabwe is particularly inept at managing their economy this is the fate of all fiat currencies as they are not backed by anything.
https://en.wikipedia.org/wiki/Hyperinflation_in_Zimbabwe