In addition, loosing the ability to track repeat customer's purchases.
secmartin writes "Researchers at Delft University warn that large parts of the BitTorrent network might collapse if The Pirate Bay is forced to shut down. A large part of the available torrents use The Pirate Bay as tracker, and other available trackers will probably be overloaded if all traffic is shifted there. TPB is currently using eight servers for their trackers. According to the researchers, even trackerless torrents using the DHT protocol will face problems: 'One bug in a DHT sorting routine ensures that it can only "stumble upon success", meaning torrent downloads will not start in seconds or minutes if Pirate Bay goes down in flames.'"