I think they can't stop the usage of bitcoin. The only thing that will make it stop is when they propose a law regarding the usage of the bitcoin. But, as long as there is no KYC needed in the transaction that you are going to do, it might take them several months to distinguish who made the transaction. They will have a hard time trying to identify who is who.
Why is it going to be really hard to identify who is who? You have your public address. They can peg your username to your public address. Thus they will be able to identify who you are without having the need of going through the KYC process.
The government can stop the usage of bitcoin, but they can ban bitcoin. They can make using bitcoin as an offence thus penalizing the person using it, but since bitcoin is decentralized, they won't be having any central authority to ban.