According to leaked images of an announcement that Valve made to Steam developers, which PC Gamer claims to have confirmed with Valve, the digital distribution platform will undergo several changes in “a couple weeks”. The message calls this initiative “Discovery Update 2.0”. While I would guess that this is the final name, it could be a placeholder that tells developers to expect changes similar to 2014's Discovery Update, which introduced Steam Curators and the Discovery Queue to the front page.
A lot of the changes, like the original Discovery Update, affect how games can be found on the front page. There will be a focus on promoting whatever the user's Steam friends are consuming as well as elevating the visibility of the “Top Selling New Releases” screen. The will also be more picky about who to show ads for new games to, which Valve expects will lead to fewer impressions, but hopefully higher click-through.
Valve will also refresh the Steam Curator feature by allowing them to communicate about titles in a more nuanced way, possibly without even making a recommendation one way or the other at all. We'll need to wait a little while and see how it is actually implemented, along with all of the other changes, but they might nudge the platform away from the visibility issues that users and indie developers alike were complaining about. At the very least, you can expect Valve to carefully measure how sales are impacted by these alterations, and continue to experiment with why.
Then we get to the screenshot policy.
Two changes are planned, each addressing a wholly different issue. The first change regards mature content. Valve does not seem to be planning to discourage gory, lewd, or offensive content, but rather force developers to properly tag their content so the user can filter out what they aren't interest in (or disgusted by). Of course, censorship could creep in with the correct mix of misguided good intentions and complacency, but that doesn't seem to be the goal, which should mean that accidents will be fixed as they arise.
The other change alters the way they intend screenshots to be used. Previously, they were treated like promotional content, even by Valve. In fact, their one example picked apart the store page of their own game, DOTA 2. Valve seems to want to change it into a glimpse of the actual game, like a demo in still image form. Basically, the “screenshots” section is turning more literally into a section of screenshots, rather than, as they verbatim say, concept art, pre-rendered cinematic stills, or images that contain awards, marketing copy, or written product descriptions. “Please show customers what your game is actually like to play.”
This all seems like fairly routine changes to me, although we will need to wait until it's live (or another leak occurs) to truly know.