Alina recently surprisingly wrote a number of paragraphs about OverSoul on the official AE Discord Server. You can read the whole conversation here: Discord Link - Alina's Statements
I'll extract and quote a couple relevant lines though I recommend reading the full thread for context and to see the efforts of the OS community over there.
Alina: I really appreciate all of the passion that you and other OS fans show. Regretably, the amount of time, work, and resources this would require is more than we have. A few years back, we did a bigger push to try to get more attention and support for Oversoul... just to see if there was the interest among enough players for us to dedicate more resources to the project. It did not pan out the way we'd hoped -- or that the community members active at the time hoped. That's hard to say, but it is the truth... and you deserve that. Oversoul in its current form won't receive updates/new characters, but I am still absolutely open to continue importing OS art into AQWorlds when and where it would fit.
It was never easy or simple to update OverSoul, unfortunately. It is a complicated project. Historically, we've seen that the game is not able to support paying its developers. That's why we had to shift team members off it. (It is the sad reality of game development; we can't afford to keep updating indefinitely projects that aren't able to cover their costs). Even having new animated characters would still require Warlic's time to 1) re-learn everything for OS set-up and 2), time to do all of the coding and release. I know this is not the happy news you were hoping for, but it is the 100% full and honest truth of why OverSoul development stopped. The game was not making enough to allow us to continue paying its developers. Even though there was a seriously hardcore group of players who loved the game, there weren't enough to cover its costs. We were losing money on it every month, so we needed to transfer the developers on it to other projects. That did not work as well as we'd hoped, or the players active at the time. Even if we had new characters made and animated, it would take more time to code and release them than we can realistically afford, when we have so many people wanting us to focus on AQMobile. I know there is a really hardcore group of players who still love Oversoul. After so much time has passed since OS got updates, it's a very small group. But they are very, very passionate, I know. I hear and see that love. My goal is always to solve problems in the best way --- in the way that makes the most sense for everyone involved. For OverSoul... That is releasing OS art in AQWorlds, because that game is still in development.
It's never fun to see a game do less than its best -- less than you hoped it to do. We always want all of our projects to be incredible, and we know you guys do, too. Sometimes that doesn't work out. Sometimes it does. I am just a rank 1 Chronomancer, and can barely predict what tomorrow will bring. I don't know what the future holds for you, for me, or for our games -- Oversoul included. What I do know is that we're still planning to be here, making games, for as long as humanly possible. And if, in the future, it makes sense for us to try an Oversoul revival, then we absolutely would. We do the things that make the most sense, that we can sustain, and that will bring joy to the community. I don't want to make false promises, and I don't want Atreue or other players to expect something that never materializes. That would feel worse than not hearing any info at all. So for now, for this version of Oversoul, updates aren't on the table, I'm sorry to say.