Initially I want to ask for more context here.
However I think you would start to see zombie companies fail and people be out of jobs, rather quickly, looking for someone to bail them out. With the governments unable to help with bitcoin. They either have to start with fiat and enforcing that people take it. If the did not there would be a huge uprising and new states built.
Even if people are using it voluntarily doesn’t mean they understand what it is and the responsibility they need to take personally if it is all there is. People wallets might change but it is the mindset that is most important.