Those who have been briefed say that under the new test, Facebook told them it will favor content that's shared by users or otherwise actively engaged with. The thinking goes, according to those briefed, that Facebook believes prioritizing content that's acted on will reduce the occurrence of fake and offensive content in the news feed.
Publishers still have many questions about the impending news feed change. Facebook told them that content from reputable publishers will also be surfaced. It didn't specify how it would define "reputable publisher" or how their traffic would be impacted, though. The worry for publishers is that such an approach will have the unintended consequence of hurting high-quality content because a lot of legitimate news articles, while they may get read, tend not to get shared or commented on.