Turkish users are naming Brakocevic and Maret. If Brakocevic is transferred, then it certainly means GS parts ways with Kosheleva. They were actually having a dinner all together last day and looked kind of like a farewell. Ataman might be considering Neslihan as OH, so Gamze can set like last year to Neslihan & Rabadzhieva to zone 4.
Grothues is registered for Chemik in their CL roster on CEV site, so she can't play CL for another club. Brakocevic is a big question mark these days.
I don't see any reason why GS would fire Kosheleva. Yes, her non-existent reception caused them big trouble in some matches, but it's not like this is something unexpected