Interestingly, until now, "light pollution" meant artificial sources. (i.e. with different colour and spectrum signatures such as CFLs, LEDs, etc.) Florida Atlantic University studies the impact of light pollution on plants[1] and animals[2] but I suspect many studies only partially apply to something like what Chengdu is doing because significant solar (or lunar) light pollution hasn't been available to study.
Just a few concerns off the top of my head that I hope Chengdu will consider or at least study if it moves forward with this: circadian patterns, melatonin production, restful sleep, feeding patterns of nighttime predators (even in cities) including exhaustion of food sources (e.g. insects) that would naturally be difficult to find.
Well this will probably improve human and traffic safety, but seriously hurt astronomy and dark sky appreciation for those who live there. And it's a given that all-seeing surveillance footage resolution will be improved!