The big gain I see is enabling more controls on smaller devices. Right now physical size is a hard limitation on the number of different control interfaces (but

The big gain I see is enabling more controls on smaller devices. Right now physical size is a hard limitation on the number of different control interfaces (buttons or screens or, for future devices with Soli or it's kin on board, gestures), with Soli though the whole volume above the object becomes interface space and the limit is the number of gestures that can be recognized.