Even if they will announce bitcoin to be illegal, they cannot fully stop it.
People can still do some transaction as long as miners are doing it, this is not a one company where we have centralized servers, this one is decentralized and it's hard for a centralized government to stop a decentralized system, which is bitcoin.

Also, I think it's not fair to stop bitcoin when it could contribute by giving a fast, cheap, and transparent transaction, in fact, they are given a help here because with blockchain everything can be trace, what they should do is start on focusing on how to regulate bitcoin.