Replacing the rearview mirrors is against NHTSA regulations. They may be used to augment rear vision but cannot be used to replace mirrors. By 2018 all cars and small truckg have been mandated to have a backup cam, but as yet cannot be used to replace..
Now that rearview cameras are being required automakers are asking the NHTSA to change the rules to allow replacing mirrors with cameras:
Goodbye, side mirror: Automakers push for cameras - http://www.cnbc.com/id/101553477