They might after a ruling in Belgium, where the local ISP, Scarlet (which was once part of Tiscali) has been given six months to begin filtering out infringing peer-to-peer content on its network. The court recommended that the ISP investigate Audible Magic, an audio fingerprinting application which dips into files as they are being transferred and tries to determine whether they are in fact copyrighted music; it can then block their transfer.
The International Federation of the Phonographic Industry welcomed the decision, saying it "sets an important precedent in the fight against piracy internationally" because it implements EU legislation - and so might mean ISPs in the UK would have to use filters too.