No turning wheels means no parallel parking. Zero turning radius would be cool, but even with complete differential steering that would scrub the tires a bit much. I don't think you could practically remove steering tires entirely. I think you're still stuck with a rack and pinion, ball joints, tie rods, strut bearings, etc so even with AWD with independent electric motors on all wheels differential steering isn't really that useful. On a performance car, it'll help with handling around turns. I don't see that becoming commonplace on average cars because of the added cost.