It cannot even be enough to cause Bitcoin to vanish. Bitcoin has been banned by some major countries in the past but still it continued to grow strong. It gained a very bad image in the past especially during the discovery of the silk road but still it recovered and even earned the trust and huge investments of rich and ordinary people alike. Bitcoin does not depend on the approval of any country. Bitcoin is an online and world currency.
In other words, Bitcoin cannot actually be banned. In words of countries' laws and regulations, they may ban Bitcoin but how could they stop people from using it? A ban on the letters will only be up to that. As far as monitoring people to make sure Bitcoin is not used is next to impossible. The capacity of the online universe to cater to people's preference of Bitcoin over fiat is very vast.