Loading a 3D model and using it for the level-base as a building that has no roof, as was done in Construct Classic by developers here, is apparently very much possible with WebGL. In the future when WebGL support matures in browsers this could look awesome!
Textured (relatively high-res), specular mapped 3D models + particle effects:
Left mouse button: rotate model in 3D space
Mouse Wheel: Zoom in or far out in space