The price quote of Bitcoin is measured in ‘stable’ coins - USDT,USDC… and not in fiat USD.
Currently USDT,USDC exchange 1:1 to USD, but this is a promise and not a guarantee, as explained in details in this article.
So, to answer the question - it is no longer possible for a single country to make Bitcoin illegal, it is going to be legal in all other countries.
However while it appears to be undercut , the fiat USD is not dependent on BTC-USDT / BTC-USDC… price quote.
In an event of cashing out - selling BTC, getting USDT,USDC , and trying to convert to fiat USD , the sellers may get less , or much less in fiat USD.
