When Star Wars: The Clone Wars was canceled by Disney back in 2013, Lucasfilm moved to tell many of the remaining proposed episodes in adapted form, using all the various media involved with what was then called the Expanded Universe. This was possible because, almost exactly a year after the television show’s termination, the EU was replaced by the Star Wars canon – now, for the very first time in galactic history, every new release would not only be continuous with every other product, but a supervisory panel (the Lucasfilm Story Group) was convened in order to monitor and maintain this continuity.
Upon Star Wars: The Clone Wars’s cancellation at the end of its fifth season, there were three more years already mapped out, if not fully written. A truncated version of season 6 (just 13 episodes instead of the typical 20 or so) ended up being greenlit by Disney after the fact and released on Netflix, thanks to the two companies’ close partnership at the time (a situation which is now completely different thanks to the existence of Disney+). To address the remaining episodes, several were selected for release in alternate forms: four further installments from season 6 saw life as roughly animated story reels (called “Crystal Crisis on Utapau”); 16 chapters from season 7 were adapted as a comic book miniseries (Darth Maul: Son of Dathomir), a novel (Dark Disciple), and another story reel (“Bad Batch”); and, finally, fragments from the season 8 – and series – finale made their way as a flashback in a second book (Ahsoka).
These storylines followed the continued – and, in one case, final – character arcs of Darth Maul, the former Sith apprentice of Darth Sidious, and Asajj Ventress, the former apprentice of Darth Tyranus. For the former, audiences got to learn how Maul escaped from his ex-master’s imprisonment, but then, in the process, lost his entire base of support – Mother Talzin, the Nightsisters, and even his Shadow Collective criminal syndicate – giving him no choice but to limp back to Mandalore, his final stronghold. And for the latter, Ventress flirts with the possibility of redemption and nearly gets her final revenge against Count Dooku, but the tables end up being turned on the assassin, and she chooses to sacrifice herself for her newfound lover – which means that Tyranus does, indeed, end up killing her, as he attempted to do so many times across so many seasons.
Given the fact that these tales are canon, and given the upcoming revival season's limited scope of just 12 episodes, it’s highly doubtful that any of these will be realized on screen. However, it seems more than likely that the “Bad Batch” story reels will be included, despite the fact that audiences have had the opportunity to experience their events, even in a rudimentary form, for the past five years; the trailers released thus far for the Disney+ run include at least one character from Clone Force 99, the Republic special forces squad that makes up the titular bad batch of clone commandos. It may even be that the four-part “Bad Batch” story arc will still act as the premiere, as it was meant to be for the original incarnation of season 7. And it’s already been confirmed that the new collection of chapters will include the series finale, detailing the Republic’s Siege of Mandalore and Ahsoka Tano’s epic lightsaber duel against Maul, which readers got to experience just a snippet of in flashback form in Ahsoka, a book that looked to transition the protagonist from her ex-Padawn status at the (abrupt) end of Star Wars: The Clone Wars to her leadership role in the Rebel Alliance at the beginning of the Rebels TV series.
Presuming that the Disney+ season consists of three four-part story arcs, that leaves just one final group of episodes unknown – and, despite the fact that Kanan Jarrus, from Rebels, has been worked in as a cameo, it's unlikely that they'll consist of an original narrative. Given just how many unproduced installments remain from the proposed seasons 6, 7, and 8, Disney has more than enough material to draw from – and more than enough material to continue to adapt in multimedia form.