They do not have the man-power to stop cryptos and Decentralized apps. They would have to raid EACH node (Miner) on the network, SIMULTANEOUSLY.
For this they will need a person at everyone's house, at a specific day/time. Which is impossible. Yes there will surely be some conflicts when the Governments try to come up with new ways to make money.

But at the end of the day, its up to the people, whether of not they want to use cryptos/dapps/DAOs.