Even though it's been out for a few years and even has a Royal Edition, Square Enix is going to keep supporting Final Fantasy XV for the time being. It was recently confirmed that the game would get more DLC, with four episodes coming in 2018 and 2019. However, a recent interview has stated that all four of these DLC episodes would only come out in 2018.
Hajime Tabata, the game's director, spoke with magazine Dengeki PlayStation (via Ryokutya) and confirmed that all four DLC episodes would be out this year. Tabata did bring up the fact that he said three would come out this year and one would come out next year but that has changed.
(Through numerous updates to Final Fantasy XV,) we have obtained the technology to develop HD games with a tremendous speed. Thanks to this, everybody has become more tenacious, or rather speedier and tougher.
(On the details of the future of FFXV within this year,) although I previously said three episodes in the last Active Time Report, we end up releasing not three, but four episodes in 2018. And that includes Episode Ardyn.
We will inform what kind of content we will provide, all at once [at a later time]. But for now, the first one will be Episode Ardyn.
As of this writing, Episode Ardyn is the only confirmed DLC episode thus far, not including the ones that are available already (Gladiolus, Prompto, and Ignis). Fans of the game are hoping to see DLC episodes for Aranea and Iris, which would be awesome.
Final Fantasy XV and Final Fantasy XV: Royal Edition are now available on PS4, Xbox One, and PC. There is also a mobile version of the game, which condenses the story into multiple episodes with chibi graphics, with the first episode available now for free.