So long as those cameras are reliable enough then they should be a good thing overall, certainly losing the huge blind spots caused by the wardrobe sized mirrors these days would be a welcome improvement.
Yes they can still be hit, but a lot less chance of clouting them than a full sized mirror housing, plus due to the less wind drag of the camera arm it will need less resistance to be being pushed in so able to be knocked in without too much damage.
I’d like to try them out, if they somehow automatically track the edge of the trailer on reversing that would be most welcome, as doing so manually on blind sides takes a bit of practice and can be a pita if you happen to be in a strange vehicle.
I suspect there’s an optional system for operators where the images from these cameras can be saved to a hard drive to compliment the standard outside forward facing and the (hopefully avoided by most of us for as long as possible) in cab camera.