Having an AC to DC converter at the mains to your house would be great. Using a reasonably safe 48V DC in the home seems reasonable. Modern high efficiency motor driven appliances all use internal AC->DC converters and a 3-phase DC->AC driver anyway. I'm still on the fence about what the DC voltage should be - upwards of 60-80 are still nice and require less current for a given load but you don't want your PC and TV to need too many stages to get low voltage.
It would be nice if some people got together and wrote a standard for DC powered homes. Preferably without a bunch of patented stuff included in the standard. Then all the pieces could be produced by various industry players and we could switch.
I have a big 48 port PoE switch (Ubiquity) and power tons of devices from it. You can get a GbE PoE “uninjector” which will give you a 5V micro USB output and use that to power tons of things all over the house, while also leaving the GbE usable at full speed (on Amazon). I also buy PoE versions of things whenever possible. I even have PoE switches powered by the core switch and home automation gear powered by PoE (e.g. Control4). Great low wattage DC distribution, and getting greater with PoE++ (I have just one 4 port PoE++ for now, but it is also 10GbE.)
It would be nice if some people got together and wrote a standard for DC powered homes. Preferably without a bunch of patented stuff included in the standard. Then all the pieces could be produced by various industry players and we could switch.