From what I've read here and on other sites and through these six pages, I suspect the following at D23.
I really feel that since the last time nothing new was announced, that something for every park will be announced, even if we know about it already. Overall, I think that they will talk about international parks quickly and then come back to US parks.
MK: More details on daytime parade, possible night time parade announcement along with new fireworks show, Dwarfs Mine Train update and success of NFL, addition of Princess Fairytale Hall. Possibly talk about MM+, Starbucks, Limited Time Magic for Autumn, going green with electric buses, new bus area.
Epcot: Success of new TestTrack, Captain Eo replacement, Spice Road Restaurant artwork, Starbucks, otherwise nothing.
DAK: Possible new artwork for Avatarland, news about Festival of the Lion King move.
DHS: Reworking of a Star Wars miniland, announcement of something in Pixar Place (please please doorcoaster), some sort of a mini Carsland announcement, announcing new shows instead of Voyage of the Little Mermaid (rumored to be Princess and the Frog) and BATB stage show (rumored to be Rapunzel), Soarin movie announcement.
DTD: You know they gotta talk about Disney Springs.
DL: 60th anniversary start up plans, upgrades to five Fantasyland attractions, something for peoplemover track (lightcycles?) and new attraction in Tomorrowland for Innoventions buliding (Ironman?), Starbucks, new parade. Talk of success of new Fantasy Faire.
DCA: Announcing phase 1.5 by doing something with Hollywood Studios Backlot (please not Monstropolis), remaking theme in Condor Flats area, Soarin movie announcement, new parade.
DLP: announcing anniversary plans.
DSP: Ratatoule coaster, Star Wars miniland.
HKDL: successful launch of new lands and attractions.
TDL: 30th anniversary parade details, possible Carsland.
TDS: Soarin possibly.
SDL: More concept artwork, announce that groundwork has begun.
DCL: General upgrades and Aquadunk for Magic.
DVC: Concept artwork and room samples for VGF, possible announcement for Poly DVC.