I don't know about this attack but all I can say is if the hack is big enough there will be monitoring happening on multiple crypto exchange, they will keep track of the Bitcoin and it's movement and yes this can take a very long time. Also some hackers are more cautious than many others, after a successful heist they like waiting it out, for the whole thing to die down but obviously none of them are smart as they thought, simply because tracking can take even years.

Hacker can wake up one day and said to himself that it's been too long already, hoping that the Bitcoin owner must have moved on or the track must have been weak and forgotten, what they don't know is that one mistake from the hacker is all they hope for, a single stupid mistake and it's all over for the hacker, bang bang on the door with tear gas and the arrest will be made.