Currently I think the most likely addition would be the scimitar mk.2, it has been passed to the devs in 2023 (pic3) and fits the hint in the dev blog (pic2).
However I could be entirely wrong and the vehicle won't be a scimitar, but the scimitar is still the most likely vehicle.
"In real life, the Turm III is a unique vehicle in that it has a 3-plane stabilizer. However, this is something we haven’t implemented into the game... until now!
Here is some more context from one of our programmers who worked on it:
Dev note: “Implementing the third-axis stabilization system was a moderately complex task that required both a custom trigonometric solution for three-axis orientation handling and deep integration with the Dagor engine aiming mechanics. The primary challenge was not the mathematics itself, but adapting the stabilization logic to support a highly unconventional control scheme while preserving precision and consistency.”
With that said, in the next major update, the Turm III will get its 3-plane stabilizer, and will be the first tank in the game with this kind. In simple terms, this means the turret will now sit level, even when the vehicle itself is on an incline. This won’t be a radical change by any means, but it will make your shots more accurate in some cases, as the reticle will almost always stay vertical."
-Warthunder Dev Blog
However, I think Gaijin will somehow use this as an opportunity to increase Turm III's BR again, which isnt good at all.