Snow and Biotopes are easily doable in A3, Biotopes is pretty much pure scripting and there were community made systems in A2 that worked close to it.
Desctructable buildings is neat, but I'll be really impressed when I see it on buildings with complex textures, as how they are doing it now seems to be a fairly simple solution compared to other game engines (but good progress).
Vehicle slippage/traction control could be modeled in A3 (a bunch of those features are already included in A3, just not fully utilized).
Remember that VBS3 brings the core of the engine up to RV4, which is A3. VBS3 has additional features on top of that.