What sticks in my craw is Falkvinge's continually disingenuous use of the word "monopoly." Owning and asserting a copyright does not make you a monopolist any more than owning a beach house on the Oregon coast makes you one. All property rights are monopolies. That does not mean owners of property rights are monopolists. Concretely: nobody is preventing someone from producing the next summer blockbuster and distributing it for free on BitTorrent, just as nobody is preventing you from building a beach house on the Oregon coast and letting anyone stay over.
I think there is zero potential for significantly eroding copyright rights, and a bunch of young people who don't produce anything themselves certainly won't be the impetus for change. At the most basic level, copyright strikes a cord with people: if I make something, I should own it and be able to control it. Young people are willing to play fast and loose with those property rights, as they always have (cutting through people's yards, etc) but that doesn't signal the impending downfall of property rights as a system.