Oh no.
Right now, Final Fantasy XV Episode Ardyn is still planned to be released in March 2019 for all platforms. However, the episodes that were planned for Aranea, Lunafreya, and Noctis have all been cancelled. All four of these episodes were originally planned for release throughout 2019. These episodes would have provided a bunch of additional story and even included an alternate ending to the main game.
Square Enix announced last night that Tabata had left the company back in October. He was also the head of Luminous Productions, which was working on the planned DLC. Tabata is now apparently looking to start his own company. Akio Ofuji, global brand director of Final Fantasy XV, says in a YouTube video that Luminous Productions is shifting from DLC development to working on an entirely new game. This news also comes just a day after Square announced a $33 million loss due to Luminous Productions.
Tabata issued a written statement about his departure.
As noted, this isn't quite the end yet for Final Fantasy XV, but it's damn close. Episode Ardyn is out in March for every platform. There is also a stand-alone release coming for Comrades but only on the PlayStation 4 and Xbox One. Sorry, PC players. There is also some Final Fantasy XIV tie-in content coming.
I've included a bunch of additional information from the press release below. Also included are some new trailers that go along with each announcement.