It's hard to say that Sword Art Online ever stopped being popular, but it was somewhat divisive for a while, especially by the end of the first season. By the time Ordinal Scale was released, however, it was clear that A1 Pictures had no intention of giving up on the franchise, and the renewed creative spirit injected into the series had ripple effects for all the studio's work.
After the success of SAO's Alicization arc, the next logical move was to adapt the currently running novel series, SAO: Progressive, a retelling of the original Aincrad arc by Reki Kawahara, to do the story again, but better. The first film, Aria of a Starless Night, was a humble start that focused on Asuna's perspective, but the next film, Scherzo of Deep Night, looks like a true breath of fresh air.
Last Time...
When the last movie ended Kirito and Asuna had defeated the first-floor boss together, just as they had in the original series. However, unlike in the show, after Kirito was revealed to be a beta tester and embraced the label, Asuna decides to follow Kirito and continue journeying alongside him. Meanwhile, Misumi, Asuna's former partner, follows in Asuna's footsteps, overwhelmed by the guilt of having left her to die before, a fate that was averted by Kirito's intervention.
The first film was an expansion on the major events of just the first two episodes of the TV series but saved from being a glorified recap film on the merits that it was from Asuna's point of view. It was just enough original, recontextualized content to make the start of SAO feel new and magical again, but it was still a retreat of old territory. The new film looks like new territory altogether.
The New Threat
Plot details have been sparse regarding Progressive 2, likely as a result of the delay due to COVID, but a number of translated trailers have given some insight into the story. The film joins Kirito, Asuna, and pals on the fifth floor where it seems Player Killing (PKing) is rampant thanks to a group that is more committed to murder than progressing the game.
In addition, the trailer shows Kirito in dismay at the revelation that certain elements have changed drastically from the beta test, namely the presumed 5th Floor boss. The most notable new character addition judging from the trailers is Argo, an agile new party member who brandishes claws.
The film is reportedly already skipping some arcs from the Progressive novels, something Reki Kawahara has addressed. Since some of those early arcs are still going, it was deemed smarter to skip the content, implying it may be told in a future film. However, the topic of skipping content brings into question how long Progressive will go on.
Could the Progressive films become a yearly tradition and the new mainstay of the SAO property? With the novels still in development, there isn't necessarily an end in sight yet, and depending on when the end does come, how many of the novels and their arcs will be fully adapted? If stories are already being skipped, how will essential info be retroactively factored in later adaptations?
There are a lot of questions, but for the moment, the second film looks to be coming together nicely. One of the most common criticisms of classic SAO was how rushed the Aincrad arc was, despite the fun had during it. There were so many places to go and things to see, and only a fraction was shown, making this particular film a big moment for fans of the anime.
Sword Art Online: Progressive - Scherzo of Deep Night, releases in Japan on October 22. There has been no update on an international release.