Yes no one can shut down bitcoin as long as there still a miner out there the Bitcoin cannot be shut down although the government can ban it they still can't stop it and monitor all of its citizen if one or few of them are still mining the government can only do is to ban it but it won't stop the person in receiving and sending Bitcoin as a mode of payment.
Bitcoin is lacking a fixed physical form and it has become a wall that the government cannot destroy, they cannot seize assets that are not in physical form, exactly as you say, the government can go to the mining sites and interact with the owners but they can't do it with all the people who are online, can't verify who is behind the addresses exchanging in bitcoin. The strongest is still our key, sometimes there are passwords that we can't remember and if we don't actively provide it, others can't access it either.