Think about what? You're gonna come up with some science fiction scenarios?
Only real possibility is that @anonsteem kept the keys / recovered the account. Else it means the hacker is the person who created the account (maybe @justinw) and decided to publicly become a 5M$ hacker.
Just give it a little more thought.
So he will create a new account. And where will he redistribute it?
Steem witnesses are not blind, they could just push another hardfork to obtain the STEEM again, but they will not simply attack a reputable exchange like @bittrex.
Good thinking.
But pushing out a soft fork to freeze those accounts to 20 sock puppet witnesses would only take a matter of minutes.
The exchanges are closed. Duh.