It's just a crackpot theory but I can't help but feel there's some weight to it and just want to put it out there in the world on the odd chance rt is just as crazy as me.

The basic tldr of my theory is that Neo is going to go back in time and replace pyrrha resulting in pyrrha's return in a later season. With the possibility of pyrrha then being the one to kill cinder and claim the fall maiden powers she was supposed to.

1. "Not where, when you are needed most" this was the line that sparked this theory for me. It implied the gang would turn up at some drastically different time period where they could have a lasting change to the narrative. But it appears to just drop them maybe a few days after they left. If the jump in time is so little why say a line like that. just say that's how long you where in the everafter. Which is why I think the lines more for neo. I think neo is going to have her moment with the tree like Ruby and be shown how Torchwick dies. Allowing neo to see that all the pain she inflicted on team rwby was misplaced and she really should have focused on cinder like she did at first. Now a ascended neo with the guilt of needlessly targeting team rwby and the anger towards cinder for inadvertently killing roman and pushing her of the ledge last season is sent to season 3 beacon.

2. Pyrrha's death was some years ago at this point. But there's always been one thing we never had an answer to. Why did pyrrha's body disintegrate? Yang lost her arm the same season and while it had a similar sparkling effect the limb was still left behind. Well neo recently gained the ability to create/mimic other people and even have them talk and be a sperate entity from her. When defeated they let of a remarkable similar effect as pyrrha's body did in season 3. And to top it all off she actually makes a pyrrha this season  that sounds like her acts like her and fights like her. So her power looks right and has already proven it could make an accurate copy of her that even her friend Ruby bought. So cinder would definitely fall for a fake of a girl she only really knows In passing.

3. "Someone once asked me if I believe in destiny" is line in season 6 cinder says to neo. While she never says to neo that was the line pyrrha said before dying. It is interesting that the only time cinder has ever recalled pyrrha is with neo and gives her the only line pyrrha says to cinder during that fight.

4. Who should be the one to kill cinder? Jaune who lost his lover, Ruby who was to late to save her friend maybe even Emerald to fully sever her tie to evil. It's a long list but neo doesn't really feel like a satisfying character to kill of cinder. Eventhough she's had multiple seasons now of being manipulate by cinder, cinder arguably killed roman and pushed neo of the edge. So neo isn't short of motivation but even still it feels unsatisfying narrative wise. In truth the best person to kill cinder would be pyrrha. Destind for the fall maiden power but was take from her. And if neo saves pyrrha which results in pyrrha killing cinder that ties neos cinder issues up and still lets Someone more fitting be the actual one to do it and What a more fitting fate for cinder than to be killed by pyrrha.

5. On top of all that cinder has bad luck with promises. The huntsmen promised to save her from her step family, she promised neo to kill rwby etc. Cinder has a line to pyrrha "its unfortunate you were promised a power that was never truly yours" which is odd because in actuality it was cinder that was promised a power that was never hers. Salem said to cinder "you will have the power I promised you when the time is right" showing cinder was promised the power and it sure wasn't hers because she had to steal it.  This ones not really proof to the theory just an interesting piece that could be nice from a narrative standpoint.

Potential holes in the theory: Why would neo not just save roman instead Having neo in the past is way to powerful How does neo swap with pyrrha Where is neo/pyrrha S4-S8

So to recap neos power looks right can accurately create a pyrrha copy, knows the only line of dialogue exchanged, has motivation to do so, the tree implies time travel, the tree can show visions of the past even if the viewer wasn't there and is narratively satisfying. At the end of the day it's pretty unlikely this is actually the case but it's still fun to think about.