That's accounting for the higher end of the 3-6% drag. Also speed is critical, because the aerodynamic effect is exponential with speed so unless you are traveling above 80mph it's barely impacting anything. Sure if you are on the Autobahn it will be higher at 100mph+ but this is a bit of an optimistic guess on their part.

Also, these car mirrors after 200,000 miles will still work. I don't know if the car "video" mirrors will be operational after 200,000 miles so the cost of replacing them can easily out run the "fuel savings" that you would expect.

Lastly, there is something that car manufacturers lose when they move away from the physical world. The parallax effect is one that others have pointed out as a key benefit that would be lost, the fact that I can get a rain spot on my mirror and still see clearly, but if there is water on my rear parking camera I see nothing is something else that needs to be considered.

Progress is great, but at some point you realize you are actually degrading the experience not improving it. The Tesla has a great big iPad to control the car, but guess what, it is super distracting, because there are no physical knobs to touch so anytime you change a setting you are forced to look down. Because there are no physical knobs your finger can not rest on anything so as you are driving on the road any bump or jolt moves your finger which makes it much harder to hit the key you want. This leads to more distraction.

Just because you can doesn't always mean you should.