I'm and "old foggy" but even I now trust cameras more than my rear view window.
Use of both are good, but rear cameras are getting to the point that they have better coverage than physically turning. We'll see with the M3 but I expect the side view + shoulder check will cover anything the rear camera doesn't?
Unless you mean for cars that don't have that, then yes.
P.S. I actually run my Bolt rear view mirror nearly all the time in camera mode. The only time I don't is at highway speeds when it's wet enough that the lenses gets dirty.