I recently saw a video of Jordan Belfort (the wolf of wallstreet) talking about BTC he was pretty much totally against it saying he thinks the govn't will never allow an anonymous (even though btc isn't anon) global currency that makes it easy to launder money.
He is such a visionary... Bitcoin and cryptos have been at least tolerated (or legally recognized) in most developed countries for many years. Does he think dollar notes wont be allowed because it is easy to launder money with them?
Of course they can, what if a government decides that all banks cannot receive any bank transfer related to cryptocurrencies? Then you'll be forced to move to a different country, or at least open a bank account somewhere else. I am sure there will always be countries friendly towards Bitcoin (for obvious reasons), just like there are tax havens nowadays (look at Belize, or Bermudes...). My point was just to say that if some countries want to ban Bitcoin, they'll do without any remorse.
That would be a major move but what we have seen is steps in the opposite direction and as you say, there will be other countries allowing bitcoin to fiat transfers, so I think there is a competition every day it is more difficult that we see such a move.