When de-centralised would be implemented with many nods running the network, maybe 1.000, across the whole world, and no centralised tools are used to execute the prime services (like the UIs), then it could be something that is very difficult to take down. But then again, the authorities could start by the users, to take them doen one by one when the eg consumer copyrighted material that is uploaded and published outside the law. When that is fought hard, other users may stop such behaviour, or may leave the service and go somewhere else. The later would be the death of Steemit and Steem.