@sivan: Physically based shading is planned, but probably after an initial release. The current shading works good enough , so for now other areas are more important.

@ventilator: rectilinearly warped shadow mapping looks interesting, but the disadvantage is the need for well tessellated meshes, because the warping has to be used on the geometry. I am not sure how well this would work for a general purpose game engine. Also there is the need to analyze the rendered scene for the warping, which would either cause a CPU stall or if everything is done on the GPU, it would still require an additional pass before the real rendering, which might be needed anyways, but still would complicate the rendering pipeline.