I'm probably the only one who isn't all that shook up about Kajiura not being involved in future Kalafina projects.
A producer is not the artist. 2NE1 without Teddy Park is still 2NE1. Kalafina without Yuki Kajiura is still Kalafina. It's a very similar situation as these groups feel a lot alike - the group having only the one producer up until they disbanded (there are very small exceptions in 2NE1 but you get the idea, back in the day, Teddy Park was almost synonymous with 2NE1's music).
As much as I love Kajiura-san's music, I'm glad I can continue to listen to Keiko, Hikaru and Wakana together again. My biggest regret in life is not attending a Kalafina concert in person, and this news suddenly lets me have the opportunity to fulfill a lifelong dream of mine. Kalafina was how I got into Kajiura-san's music, and call me a Kala-stan or whatever, Kajiura hasn't really created anything impressive since Kalafina disbanded in 2018. Even towards the end of their tenure (pun completely intended with 10-year), I could see Kajiura running out of ideas for Kalafina. No new "studio" album released after FotW was the biggest indicator. But I still listened because I love their voices, individually and together. The best thing to come out of their later years was by far the Christmas album, which highlighted their vocals much more in a way that previous albums didn't.
It'd be nice if Kajiura could relinquish control over Kalafina (well guess she doesn't have a choice now). Kajiura always had a specific view in mind for how she used each member and what song an part they'd fit more at singing - at best, we got songs like Red Moon, destination unknown and Magia. At worst, when she pigeonholed each member to their own part, pretty much plateauing any growth they could have had as a vocalist, we have songs like blaze, believe and heavenly blue. Even now she still pigeonholes Yuriko Kaida and Keiko.
I'd prefer Kalafina to go the route of having multiple composers with their own ideas of how to utilise each member's voice. Wakana, Hikaru and Keiko write their own songs now, and I'd love to see them try their own Kalafina song. Switch the harmonies around so it isn't always Keiko on low harmony, Hikaru on middle and Wakana on high. The only time I've seen Wakana do low harmony is love come down and elemental.