But I don't think that's WOTC's endgame here, anyway. More likely there are strategic considerations involved on their part that probably play a bigger role than actually getting, and collecting on, a judgment. This could be a shot-across-the-bow move by WOTC, for example, with them firing on the first people they were able to determine had uploaded based on the watermarks. Whether that's viable or not is certainly questionable and open for debate, but WOTC certainly doesn't think they are going to collect millions from a few individuals in Poland or the Phillipines.
We both see that this move isn't about lost sales, if it would be, they would still sell OOP material as PDFs, they simply doesn't want to sell PDFs. And I can't even blame them for this.
Why?
They see even if 4th edition is considered a success and is sold to some new players, several old players don't like it, and if we see 3.5E crowd getting books (endless supply) and many will buy Pathfinder RPG that is bad. Also PDF sales on RPGNow / DTRPG and D&D Insider based content distribution can be direct competitors of each other.
If this will be aproblem in near future, then any high profile pdf getting pirated is a good excuse for it. If they just speak about piracy that is there for ages, that isn't strong enough. If they sue pirates they can point to... Now that is better.