Yesterday's Rear View Mirrors

Has anybody thought of or is a system in use now that is similar to the backup camera on the back of a vehicle that transmits an image to a monitor on the dashboard  in that a camera on the back of a vehicle, possibly integrated with the third stop light on the vehicle would transmit an image to a monitor that would replace the rear-view mirrors on a vehicle ?   I would say this concept would be something to consider for the future, maybe even dual rear-facing cameras.