No, it's got nothing to do with power over ethernet.
It's simply having only one high power rectifier at the breaker box.
And removing all those rectifiers from every device in the house.
We don't need AC in the home anymore. Every device is now using DC, and any other device will still work with DC.
The only thing really left are motors, but even those are going brushless and we can chop half of the inverter out of the equation of those as well.
And every device won't even need smart electronics for PD either.
It would also solve the North America 60Hz and EU 50Hz issue, where the AC coming in doesn't matter. We all standardize on a DC output.
And when people want to add alternative power (Solar/Wind/etc), it's a HELL of a lot easier to just push the DC into the existing system without having to worry about frequency matching.