As far as we know there is no super-computer exists today that can play this game anymore.
I don't want to give false sense of security though. The risk exists. For any private entity who can beat network's hashing capacity it would be more profitable to mine instead of trying to corrupt the blockchain. Any pool close to or over 50% poses risk of being hacked for instance and screwing the system. Don't know what to say about authorities - would they want to screw with it in such a way instead of simply trying to outlaw it if they deem to do so.