According to sources, the season preview which happens after a gap of every three months is a new initiative by the developer which is no way, a replacement for their videos and blogs that they usually do. They did reveal about never creating something so unique before and hence were really excited to share the content with all the forums members. 

The origin post from the Sims forum was eventually covered by simsvip, where replies to the post by the players themselves, hoped for something new in terms of add-ons like restaurants, vampires and pets which were apparently in the interests of most of the players.

However, the game's global community manager Drake, apparently hinted that new content would be arriving this week through his twitter feed when prompted a reply, indeed confirming that the game will see another seasonal preview which is due sometime this week. As of now, it looks like nothing much can be assessed from tweet but as per public speculations, it can either be an update or a separate DLC with additions of some in-game new packs.

As per reports from idigitaltimes, the character  pack might come in the form of a patch in december which will be a part of Holiday Celebration Pack. If at all anything will be revealed, it definitely has to be a teaser for future content that the players are desperately waiting to see.

The last preview which took place in October hoped for pets and season DLCS but however everything went silent after a Sims developer hinted on reddit about two packs that's reportedly in development.  As of now, nobody's assuming anything and everyone are patiently waiting for the developers to reveal what it is, this month.