Up until now, crypto transactions are still small compared to fiat transactions. So I don't see it as a replacement for fiat transactions especially that governments will still keep their local fiat, because they have the full control of its existence. We may see crypto adoption but it doesn't mean, it is going to displace the local currency of the country. Unless, the government itself declare that crypto or btc is their main legal tender.
Yes, crypto transactions are still small compared to fiat transactions because many of the countries are not yet accepting the possibility that bitcoin may be used as another currency that will be circulated in their economy aside from fiat. So far there's no clear evidence or study that will show bitcoin will be a danger to the local economy but if it would be proven I think the Local economy will not only be the most affected but also the international fiat that used today as a means of the main transaction like $. In my own perception if bitcoin will be used in a wide adoption it would be first used via international trades.