Ame is technically doing something new in Vtubing, especially Japanese Vtubing. So, no one really knows what it all means yet. However, this isn't new in other industries. Regulars leave TV shows and come back for 1-2 episodes quite often. The Professional Wrestling Industry does this constantly. The fact it took this long for it to happen with a big Vtuber is a little sad.
Ame is retired from Streaming as Ame. She will pop back up occasionally & in a bunch of future projects that were already in the works. But she is free to do other things without any direct job requirements. She likely has a version of the Sustained Contract that members like Coco and Aqua has, as there is still YT revenue from their channels and really complicated revenue around their Music.
So, yes, it's confusing to both English and Japanese speakers right now because no one knows exactly how this'll play out.
I doubt the investor call had anything to do with this. Yagoo has had to give that same statement to a bunch of people over the last 7 years. But it's a de factor graduation. Functionally, it's a retirement from activities and she'll no longer be a direct streamer contracted employee of Cover. However, there's sustained contracts around residuals, long term channel revenue and music rights. In some ways, the retirement contract might actually be more simple to manage than the graduation one.
I get the distinct feeling Ame might just go deeper into the VR space. Maybe she crops up as a VR Tech Tuber and we somehow end up in the weirdest LTT collab video we've had in a while.