Thanks for all this insight, this is why HN rules. What is your impression of law enforcement, everyone claims to reach out after an attack, but I've never seen follow up of sucessful law enforcement activity resulting in arrests or prosecution. Thanks again.
Law enforcement is currently attempting to ascertain whether or not the actor is within the US. If it's within the US, I (personally) believe there's a good chance they'll take the case on and presumably with enough digging, will find the attacker. (The people involved seem to be... pretty good.)
But if they're outside US (which is actually reasonably high probability, given the brazenness of the attack, and the fact that they're leaving a lot of exhaust [e.g. IP address, phone number, browser fingerprints, etc.]), then my understanding is that law enforcement is far less interested, since it's unlikely that even an identification of the hacker would lead to any concrete results (e.g. if they were in North Korea). (FWIW, the attack was not conducted via Tor, which to me implies that the actor isn't too worried about law enforcement.)
To give you a sense, we are in an active dialogue with "professionals". This isn't a "report this to your local police station" kind of situation.
FWIW engaging simultaneously with both the FBI and the USAO/DOJ and putting pressure on DOJ to act on the case typically results in better outcomes than just assuming the SA assigned is going to follow through and bugging them about it.