Every single attempt to make a popular VN into a franchise (ML, Grisaia, Higurashi) was a fucking failure. Everybody wants to make their next "Fate" but they don't get the concept of Fate a.k.a Grail Wars is so flexible that you can make a billion stories out of it
Like who the fuck cares about the other quirky CIA agent heroines in the Grisaia universe? And Higurashi? You can only recycle the same story once, and we know how the reception to GouSotsu was so Ryukishi's brilliant plan was to make another one but call it Silent Hill instead so maybe the normies who arent aware of Higurashi will enjoy it. And Muv-Luv, yeah, it had legs. There's decent worldbuilding here and there, but at the end of the day it's still a Starship Troopers clone and most of the original VN's appeal was Takeru and Sumika's story. None of these are "let's make a gacha, and get rich" material.
Don't even get me started on Aokana.