Surely you could spend this time creating textures and models? Even if you're not currently working on the engine there's a lot that could be done.
Not much of the rendering and lighting engine is intact in the Dota 2 version of the engine, so we don't know really anything about how textures need to be authored, maptypes, etc.
If the VR presentation was anything to go by, there's a bit of proprietary methods that are going to require authoring assets specially, something we can't do since no documentation has been release, and because it's not in the engine yet. Aside from textures and materials, we don't know polycount targets, or best-practices from valve; it would be going in blind.