I've told you all before that Kalafina has known that they're going to end by their 9+one concert. That 9 being their 9th anniversary and +one as their last one year together but you all didn't believe me so (shrug)
Tbh I really don't see Wakana joining Kajiura again. Wakana leaving Kajiura was the best choice for her. She's expanding her horizon, she sounds very good live compared to her Kalafina days - heck she even sings Kalafina songs better now, her fanclub just started kicking in, she's making more money due to working alone, and she gets a good amount of promotion. She has said before that Kajiura scolded her the most (a statement that is also confirmed by Kajiura), so I think even though she's very grateful for Kajiura at the same time she was very stressed working under her. This is all speculation here, but It's stressful always getting scolded even though it's for your own sake and we all know that Wakana is the softhearted one of the group. I too would want to see Wakana singing with her KalaFJ friends but her choice and well being came first.
Working for Kalafina is also already unhealthy for Kajiura because you can tell how less effort she put in her works and how she said that in the past years she's been working like robot, not able to make songs that she really wanted to make.
Tldr: they're all doing good by this point. I miss Kalafina as well but they've made their choices and it seems that they're very happy with their choices. Good for them. If they ever reunite, good for us and good for them even though it's very unlikely.
PS: that love affair drama in Spacecraft that's said making Kajiura's manager and then Kajiura leaving SC? Juicy. Very k-drama ish.