Take my words as a grain of salt as I am not a PI engineer (I work as an SI) and its early in the morning but I don't think we are at the stage that we should be using 48v supplies for consumer electronics.
In the next 5-10 years? Sure. Not right now. Downing 12v to 5v, 3.3v, and 1v is fairly uncomplicated and cheap. The same cannot be said for 48v supplies. Sure its the same idea, but components have less tolerance to fluctuations meaning that things can go very wrong very fast if a consumer lives in an area with a bad power grid or in a house with cheap wiring. Along with this it brings the costs up by a good margin as you need better components to make it work efficiently. Take for example a cheap 500w 80+ (no metal rating) ATX powersupply. There is a good reason those dont cost more than $40-50 USD. They dont require the best components and can be made dirt cheap (those psus only cost ~$20-30 USD to manufacture, the rest makes up R&D, marketing, and profit after those are sorted out) but as we get higher in efficiency the price rises exponentially with 80+Titanium being about 10-20x more expensive for R&D and component costs than the 80+.
Now take this to 48V supplies. You need better over/under current/voltage and power surge protection, you need better down converters, you need better components in general. Now take the heat into consideration. Converting requires a loss of energy which translate into heat (pretty self explanatory) but its more you need to cool meaning a bigger heatsink, faster fans, etc... Sure efficiency is better on a large-scale like a supercomputer setup with multiple XEONs and GPUs in large clusters, but for a consumer device? Its not really all that feasible. You can make the argument that consumer electronics already use 48v supplies (A/V equipment) but its not the same complexity. Those supplies downvolt to a specific amount and that amount only for its use case, we arent splitting a 48v supply into 5v, 3.3v, and 1v. The most reasonable thought would be to split a 48V down into 4x 12V and split accordingly to spec, but you just created something that now requires 4x 48v-2-12v converters along with 4x the converters to go from 12v to 5v, 3.3v, and 1v if you dont plan on making each 12v connection only convert to 1 standard voltage.
Now then I can already tell you some of what I said is incorrect, but im going off some assumptions ive seen in the industry and my work with other PI's [Power Integrity Engineers] as well as my knowledge as an SI [Signal Integrity Engineer].
Also as im thinking about it, higher voltage wouldn't mean smaller wires. Voltage affects wire insulation and Current affects inductance. So sure you save on the copper, but your trading it off for more insulation around the wire. Its less insulation by far than what you would need for copper making the wires "smaller" but it wouldn't be that much noticeable for say 8-pins for example.
