There is no way a 24-600mm eqiv lens in a camera with 1" sensor would have a constant F2.8 aperture. The RX10 III has the fastest (F2.4-F4) and longest lens of all 1" superzoom cameras. Sony will keep the RX10 II in the lineup for people who don't need such a long zoom.
Update : My UPS guy just dropped it off so I went outside and did a quick test on a dim, damp day.