I've been wondering the same thing... Besides, there are other differences between lab environment and the "real world" - actual water is full of impurities (e.g. limescale, urea in pee, mud, salt, acid rain, ...), I wonder if the material retains its hydrophobic properties. The other thing that worries me probably even more than "wear-and-tear" (i.e. scratches, abrasion, ...) is dust - once dust covers the fine nano-structure, water will once again stick to it, and it might well be impossible to clean!