i mean, the logical thing for Sony to try and kill next is the lens AF mechanics.
Maybe they need to keep the A mount alive for the extra flange distance it allows (requires), or some other physical parameter which is superior to E mount. It's dumb to kill a mount spec if you can reuse it, all that precision tooling and testing ...
Edmund
The advantage of the E-mount isn't the mount itself, but the possibility of a short flange distance, allowing for the use of a much wider variety of lenses. But it's possible to keep the A-mount while shortening the flange distance to allow for the use of lenses with short flange distances, by using a movable sensor (and, with IBIS, the sensor is already movable). Keep the same socket and just move the sensor back and forth, to suit whatever lens is plugged into it - 46.5mm if you're using a Nikon F-mount lens, 44.5mm for A-mount lenses, 44mm for EF-mount lenses, 27.8mm for Leica M-mount lenses and 18mm for E-mount lenses.
Thing is, third-party lens compatibility is vital if Sony is to expand its market share - something that E-mount allows, but a non-movable A-mount would not. Being a latecomer to interchangeable-lens digital stills cameras, most people out there already have a collection of Canon or Nikon lenses they would be very hesitant to abandon in order to switch to Sony, no matter how good they make the cameras. Also, Sony itself does not have the expansive lens collection of either Nikon or Canon, making it much less attractive to newcomers without a pre-existing lens collection (sure, there are some ancient Minolta lenses, but, in the current age of high-resolution sensors, these are more relics of the past than working lenses that would be of interest to photographers investing in a new system). As such, they have to poach Nikon/Canon users and convince them to invest in Sony gear instead. But the need to abandon their existing gear is a huge barrier to switching. E-mount, allowing the use of third-party lenses, mostly removed this barrier. A movable-back A-mount would do much the same.
With regards to moving the sensor for AF as well as for flange distance adjustment, this has the disadvantage of altering the magnification of the image, sometimes to a large degree - for instance, when focusing close, a lens that is nominally 300mm could end up giving the same angle of view as a 240mm lens, or even shorter, if you had to move the sensor much closer to the lens to focus on a nearby object.