There’s a first teaser for the upcoming, presumably final DLC.
Ignis Scientia, a companion of Prince Noctis from the original Final Fantasy XV, will be the main hero of the upcoming expansion. Right now we can confirm that the DLC is expected to release near the end of this year, in December.
The Season Pass for Final Fantasy XV offers access to three “Episode” DLCs, with Gladiolus story already available and Prompto add-on releasing this week. There’s also a Multiplayer Expansion: Comrades planned for the future.