So anime/gacha games would be even less likely to support SKG, compared to even Concordverse games, since Concord (and later Highguard) wasn't brought up at all when SKG started? Granted, Concord players did attempt to create private servers for the game, but Sony DMCA'd them.
What exactly do you mean by "anime/gacha games would be even less likely to support SKG"? Are you referring to the Asian companies that produce the anime gacha games, or the fandoms?
If you mean by the companies, then it depends on the company. Four of the five major Chinese gacha game companies (Mihoyo, Hypergryph, Manuuu, Bluepoch) are privately owned (Tencent now owns the majority of Kuro Games), and the gachas they are run are their own wholly original IPs owned by that company. So it is really up to the company owners if they want to keep the lights running or to do an offline rerelease, and the company owners are very keyed into trying to please their fans. I could easily imagine them trying to make sure that people could keep playing Arknights or Reverse 1999 if the servers were shut down, though more than likely they would just try to keep the lights on indefinitely. Mihoyo and Hypergryph are already fabulously wealthy having made their gacha billions so that's not a question for them.
This is more of a problem with the Japanese gachas, which are usually not original IPs but are licensed, usually based on anime that are already owned by not one by several different companies due to the production committee model. You have Kadokawa or Shounen Jump who owns the original manga or light novel, you have the music company, etc. Lots of companies have partial ownership, except the actual animation studio. They almost never have any ownership. So you would have to get authorization not from one otaku but also from several boomer suits who don't care about fans and just making a quick buck or his next quarterly report. Octopath and Atelier did not originate as animes but as videogames, so that reduces the number of actors involved who all have to agree.
So you're having to go up against a corporate buercracy, and I just don't see them wanting to bother with this if it does not seem clearly profitable on paper. And they are not going to officially endorse private servers, so it would be up to invidiual game devs if they want to risk leaking files. A former Shadow of the Colossus dev was secretly leaking dev files until that caught some attention, and then he went dark for fear of repercussions, and that was a game from 20 years ago you would think no suits would care about anymore.
If you mean the fandoms, then they would only care about preserving a handful of games, usually the big Chinese ones, and maybe a couple of the bigger original Japanese ones like Granblue or F/GO. You don't see people expressing nostalgia over the game experience of licensed cashgrab gachas like dragonball or most of the old Final Fantasy gachas.
Another major issue is the gameplay, which is not uniformly great. Exploration tends to be fun, the event minigames are usually very entertaining, etc. But the combat is almost always a mixed bag. There are a lot of reasons for it, but in short the traditional gacha monetization model (aka your game is being kept afloat by the 1% of rich people who will casually throw thousands of dollars at you, you have to reward them somehow, usually by letting them pull for dupes that makes their characters way stronger), the live service mentality (they desperately want to habituate people and keep them logging in and thinking about the game every day, so there are stamina and RNG relic substant systems that comprise the gameplay progression), and having to be playable on phones (restricts how many buttons can be placed onscreen and thus how many abilities characters can have and the depth of the gameplay) constrains the gameplay experience. Aside from maybe ZZZ, the actual combat experience in these games is usually not as engaging as contemporary box purchase titles like Trails or Granblue Fantasy Relink. People usually like these games for the other aspects like the characters, the aesthetics, the soundtrack, the minigames, etc.
So that would somewhat diminish interest in preserving the games, though for the big ones they are overall of high enough quality that there would be a lot of sorrow if they stopped being available. But without server access, for a lot of them there would be just no hope for fans to preserve them on their own. Granblue Fantasy for example does not run on an app but in your web browser and CyGames' backend servers handle almost everything, sending you the images and voicelines to your web browser rather than having them download them to your phone or computer. If the plug were pulled, how do fans possibly make an offline version of that? Etc.
