Sigma fp is smaller but does it count? No mechanical shutter and no hotshoe.
FF sensor on crop sensor body is tempting but I'm not in the market for a new camera. The $1900 price tag also won't tempt me to upgrade my a6400 for this. For someone who doesn't have FF body it might be tempting but there is still a lot of difference in price even to the a6600. So I do disagree, it won't kill Sony's crop segment, especially when you count in the price difference in lenses.