I think it's highly unlikely we'll see mass scale retrofits, but if enough momentum builds up, I can see it as a great bonus feature for new builds.
I got lucky with my house and every room has a dedicated phone line meeting at a distribution panel (a couple of 2x4s with screw terminals) built in the 50s. I'm in the process of converting it to light duty DC power. The wiring is only good for an amp or two, but at 48v that's still significant power transmission.