Some of the suggested solutions here go to the very heart of the thread topic. Even if technically feasible, which they are not, the solutions proposed are draconian and incompatible with democracy. None of the technical measures suggested are close to perfect. They differ only in the number of people they do prevent. For example, the so-called Great Firewall of China is a success in the sense that it seems to work in censoring the net for the vast majority of its citizens. However, as is the history with such technology, it is in a continual war with those wishing to circumvent it. Anyone with a reasonable grasp of the technology can still circumvent it relatively easily. And projects like Tor, Freenet, etc. in working to protect privacy and freedom of speech, incidentailly make circumvention and protection of piracy easier for more and more people. See, for instance,
https://tails.boum.org/. The UK decision blocking the Pirate Bay is laughable. After a major effort the Court was persuaded to make orders which are totally ineffective, as they are defeated by something as simple as a proxy. Likewise the Australian Government's ridiculous proposed blacklist, which hopefully will never be implemented.
Piracy at the moment is relatively mainstream. Any serious attack on Torrents, Usenet or other sources, even if effective, which I doubt, would simply drive pirates and those utilising them to either new or existing darknet technologies. If you doubt this download Tails, run it as a livecd and visit, say, the hidden wiki. There you will encounter links to hidden sites which facilitate some of the worst types of criminal activity. In fact, whilst looking at the Wiki itself is harmless, I suggest you might want to think twice before visiting some of the links. If they live up to their descriptions even accessing some such sites is illegal in some countries, not to mention sickening. Yet law enforcement has proved impotent to identify visitors and take down such sites, with the rare victories I have read of being the product of carelessness or stupidity. Look at bitcoin, an internet currency, being used now for anonymous transactions, many of which no doubt are used to fund illegal purchases or activities. These are the areas where pirates will retreat to if really hard pressed, which does not seem to be the case at the moment.
The best thing to do is to accept that there will always be some piracy. If the whole internet was to be shut down tomorrow, there would still be piracy. Be thankful that human nature is not as bad as it is painted. People are still buying books, and there is money to be made. Despite the bleating of the large Publishers, they remain profitable. Judging by this board, virtually all members are paying for their books. I am certainly still contributing regularly to the evil Amazon, though I have not bought a book subject to Agency Pricing and will not do so. If there is an agency author who releases a book I absolutely must read I can wait until prices come down, go to the library, buy used copies or borrow from friends, assuming, of course, that I resist the temptation for instant gratification. So far, the issue has simply not come up. I have been so pleasantly surprised by the quality of cheap and even free fiction available and I now have a long and growing queue of such material on my Kindle.
To the big publishers I say accept that there will always be some piracy, and the losses at the moment are far less than you make them out to be. The best way to minimise it is to respect your customers, make it convenient and easy to purchase your products, and keep prices reasonable. Also, respect your authors and pay them a decent share. If you don't, they will eventually go to Amazon, Smashwords, Lulu or any of the myriad of new entrants who will step in to fill the gaps you leave. Yes, you will have to endure much lower margins, but technology offers the potential for much higher volumes and, of course, big savings in costs. Amazon will only become the monopoly you profess to fear so much if you fail to adapt and compete.