Basically, current harnesses run at 12V and use MANY wires in them. You can cut that down drastically by moving communication over 1-2 wires, but at higher voltages. But it requires a new bus system, as the old simply won't work.
Tesla talked about it back in 2019, there is an article here:
Tesla has revealed its revolutionary new wiring architecture that enables more robot automation in the manufacturing process and uses fewer...
electrek.co
It would cut down on weight, complexity, etc. But it would be a substantial change, and would require module vendors (airbag, sensors, etc.) to all be on board. Old modules would simply not work.