"This sort of back-and-forth battle between the open source ad-blocking community and circumventers has been going on since ad blocking was invented; so it's very possible that Facebook will write some code that will render the filter useless -- at any time," Adblock Plus' Ben Williams wrote in a blog post. "If that happens, the ad-blocking community will likely find another workaround, then Facebook might circumvent again, etc."
Williams also notes that the filter hasn't been heavily tested -- Adblock Plus will adjust it based on feedback from its users. Facebook, naturally, isn't so keen on the update and points out that it may be blocking regular posts. "We're disappointed that ad blocking companies are punishing people on Facebook as these new attempts don't just block ads but also posts from friends and Pages," a spokesperson for Facebook told The Verge. "This isn't a good experience for people and we plan to address the issue."
It makes sense for Facebook to take a stronger stance against ad blockers, since its business is mostly dependent on ad revenue. But the swift response from the ad blocking community makes it clear this isn't a battle Facebook is going to win anytime soon.
Update: TechCrunch reports that Facebook has already begun rolling out code that will disable AdBlock's workaround.