Well, this case is a little more disappointing than you might think. Prenda's in so much trouble because they falsely represented to the court that they had an unrelated, copyright-holding client, when in fact they held the copyright (and kept all the money) themselves. No one is challenging the model of "own the copyright to a porn movie, and then sue people who download it" (although it has also been suggested that Prenda was the source of torrents for its movies, which would complicate its claims).
It cannot be proven that Prenda was responsible for the torrent in the first place (an IP address is not enough for proof of identity) but it's pretty much settled at this point that Prenda paid for the production of the pornography, had no intention of ever releasing the pornography for consumption, and posted the original torrent so that they could go after "infringers."