The coins are gone forever, sad but true.
Lets say these cyber-detectives track some of these coins on to an exchange, where the thief is trying to sell them for fiat. What are they going to do? Contact the exchange/admins and say "there is a user on this site selling stolen coins". The exchange wont do anything. If the thief was remotely smart he'd sell them outside of an exchange, or like someone posted before launder them through alt coins and changed addresses (super easy to do).
If the admins do something, that would destroy the whole bitcoin system. Transactions are meant to be irreversible, authorized or not. If we make a special case for someone, more will follow.
Exactly. I guess my question of what will they do was more of a rhetorical question. It's a theft and a crime, but at this point there isn't anything these guys can do outside of luckily finding the person in real life and having some fun with him/her/them.