We already have an icon to display the view from the rear camera. Implementing icons to display the view from any of the side cameras should be an easy patch. When backing out of a tight parking slot in a parking lot, the rear camera isn't useful to see adjacent cars or obstacles on the side. I've gotten multiple scrapes and dents in cramped indoor lots.
And even better, provide the option that will show the left or right hand camera, when the driver indicates to change a lane on a freeway e.g. over a certain speed i.e show the blind spot (if that would show on the camera).