My last car (BMW E61) rarely had working parking sensors. I replaced the module, 2 looms and all 8 sensors at a cost of over £1600. A single sensor (paint matched) was £120.00 from BMW. First time they failed I had to pay an auto electrician handsomely to diagnose which had failed as when one fails they all go off line. For subsequent failures, I diagnosed these myself using specialist software that had to run in a virtual machine, then get to grips with bumper removal to replace the sensors, depending on the location of it. Sometimes I got lucky and only had to remove a headlight.
Needless to say, if a comparable solution can be developed that doesn't require 8 individual pieces of hardware to work consistently, plus the looms, then no sensors is surely a more sustainable option. We'll have to see if Tesla manage it.