A gacha is probably not out of the question but I don't see how they'll have enough 'content' for it even if we consider everything they got. That said, I'm kinda ignorant on how much actual content you need, guess a solid foundation helps in any case.
>>280226532
If you mean the VN, then yes and no, the concepts and characters within Kamitsubaki are going to be more or less the same but the story itself is already different.
The rhythm game also has its own story bits set in Kamitsubaki City, but that one is more about the Isotopes, the characters that are made for witches' synth voice banks, pic related.
>>280203538 this game, MONARK, got nothing to do with Kamitsubaki lore, the witch girls just did the OST for it.