I'm betting on Kajiura cause as I said on my previous post before, she rarely praises her songs on twitter but when she collab w/ Kajiura, she goes super noisy lol. Sawano with Aimer is possible too since he releasing album too(But please no Image kinda song...I really like all their collabs but not that one)
Considering the schedule as well as the recent statement by Kajiura on her way of composing (if we understood the meaning correctly), more likely Sawano. But as you’ve said, when the singer praises and talks about emotion, Kajiura is often nearby. And a singer’s inner core isn’t much revealed through a Sawano (and lyricists) song, so he/she wouldn’t identify himself/herself with it - I would be disappointed to be wrong.
My prediction of collabs this 2021 since I'm bored lol:
More Kajiura x Aimer (Not just the wonderland song)
Kajiura x Reona (It will happen sooner or later anyway)
Kajiura x Uru (I see signs uwu)
Whoever (Claris/Trysail) will sing ED in Madoka if announced early
Kajiura x TRUE (I think Kajiura is aware and potential collab if manager-san agreed mb)
Kajiura x Keiko (Only IF Keiko ventures in Anime OP/ED my loyal girl would probably want Kajiura to compose)
New Fictionjunction + Artist in an unknown animu we speculah
lulz no but WHAT. IF.
One idol female group (ex. Bang Dream! / Aquors? since I said so + clout)
Aimer could be the one to sing for Madoka (Walpurgis Album - Madoka) I've connected the dots guys OMG
Vtuber collab (if manager-san knows wats up in industry he could make it happen)
Kajiura x MAPPA/Kyoani (Kyoani possible if collab with TRUE lol, MAPPA since they are rising in popularity)
Well ya I just realized it before but kinda complicated since Madoka sequel is still in limbo (I'm talking mostly about the staff like Urobutcher which I think still busy with other works + SHAFT staffs quitting) but hype is there and I think something will be announced that won't disappoint Madoka fans. But anyway, as much as I like Aimer x Kajiura collab, I wanna hear other artist collabing with her and if Trysail would be announced, it has been a while since she did song for voice actors right? Might be interesting!