I've just tuned into a pre-recorded special announcement, in which plans were discussed regarding the future of Final Fantasy XV. I'm updating this post as I listen:

1. Episode Ardyn is schedule for released in March 2019, but the other 3 episodic DLC of Aranea, Lunafreya, and Noctis have been cancelled.

2. This is in large part due to the FFXV team who were working on these titles moving on to Luminous Productions and proceeding to work on the as of yet announced new triple AAA game title.

3. As of October 31, 2018, Hajime Tabata has resigned from Luminous Productions and Squre Enix. He has decided to start his own business to work on a new project.

4. It appears Episode Ardyn will have a short animated prequel before the chapter comes out, perhaps like the Brotherhood anime but just a singular episode? Not sure.

5. Even though the other 3 DLC chapters will not be released, they still want to convey the story they wanted to tell from those chapters in "Some way, shape, or form".

6. There appears to be an expansion being added to the Comrades multiplayer in Decemeber. Added bosses, etc

7. Final Fantasy XV and XIV crossover! Miqo'te character gives out quest, and Garuda shown as a boss. Trailer at 22:30.

At 13:26 is a teaser trailer for episode Ardyn.