I like the idea of LiFi communications. Might be hard for devices to upload data, but beaming stuff from your light bulbs down to your devices might be a very high bandwidth possibility.
My imagination is getting ahead of me, but you could potentially have lightbulbs+LIDAR in your roof, to track occupants and things.
The current issue is because light is line-of-sight. Such systems traditionally need a lanyard of some kind to provide unobstructed access, and this is super inconvenient for the user.
Then there's the problem of means-of-detection; Phillips had a cool setup that relied on the rolling shutter of phone cameras; but as soon as someone comes up with a global shutter for phones, such systems are toast.
My imagination is getting ahead of me, but you could potentially have lightbulbs+LIDAR in your roof, to track occupants and things.