Yes, and many of the services available to exchange cryptocurrencies are P2P (like AirTM). It's very difficult to track and control such services, even more if they work from outside the country.

However they are just partially decentralized. I'm still waiting for the arising of blockchain solutions for trading currencies, completely decentralized. I know that they will appear soon; it's just a question of time.

Such decentralized services would be impossible to take down, as it is impossible to take down any worldwide blockchain.