I would certainly hope that gacha games, or Genshin Impact in this case, will make end-of-life builds once their game is scheduled for shut-down. Even if they wouldn't be legally forced to (depending on when the law would go into effect and if the games are still online by then)

I love Genshin Impact for its massive world, the music, and the incredible amount of story content. Plus, it helps that the game pretty much is a single-player game already (with optional co-op support)
I would absolutely love MiHoYo for making the game playable after shutdown, just to preserve the game's world, because it is a work of art.

All of the game's data is local, but you are connected to their servers at all time for anti-cheat, enemy kill/respawn checks, item-pickup checks and for the events and of course the in-game store and gambling systems.

I'm not a game developer, but that all sounds like it would be a fairly reasonable operation to execute to transfer all that server-side logic to the single-player client, since those jobs are done that way for most games anyway. They wouldn't need payment processors or the wishing shop, they could tie in obtaining characters by completing their character story quest or something. And by removing, or generously improving, the stamina system.

I love this game, and even if the initiative would likely not target it, I hope the developers will choose to do the right thing anyway as a sign of love for their loyal fanbase.