Now that incandescent bulbs are almost gone, I wonder if it will become common to have wires carrying DC in the ceiling instead of every bulb having to implement the AC to DC conversion as cheaply as possible.
Unfortunately, Powerwalls and other similar products are made with built-in inverters and connect only to AC, there is no DC tap. And there aren't any standards around DC wiring and small appliances, so it isn't likely to get traction.
I'm mentioned before (https://news.ycombinator.com/item?id=21109247) that I've seen a DC installation at a friend's house, he used 12V cable lights and DC bulbs, so it seems to work.
Imperceptible if you are just looking at it, but in a dark room if you move something quickly in front of it you can see the strobe effect.