Players can look forward to two new dungeons, the Saint Mocianne Arboretum and a hard mode for Pharos Sirius, along with the new 24-person content in the form of the Void Ark. There will also be a new Gold Saucer entry added to the challenge log, more main scenario quests, and new housing options like the ability to adjust your house’s interior lighting and brightness. While the quick translation from the live letter doesn’t perfectly translate everything, it should whet your appetite for more official and formal previews in the weeks to come.
Source: Official Site; thanks to Drakonicus for the tip!