The full frame mirror-less A7 range has been getting better. Its main issues have been noisy shutter, vibration, a slightly inferior RAW file that seems to do some internal lossy compression before saving.
While I admire the continued efforts of Sony with these endless releases of ever improving cameras I also feel sorry for people that buy Sony gear and then six months later they release a better model. I also find it irritating that they release cameras without battery chargers and lens hoods are often an optional extra.
Currently my full frame needs are met with my Nikon D800, and one day I hope a Leica M9 or M 240 so while my GAS (Gear Acquisition Syndrome) wants me to buy one the limitations and the fact that it would just duplicate my Nikon and Leica system stops me.
Still if your after full frame and autofocus in a small package its hard to ignore.
The truth of the matter is that within ten years cameras like the low end Nikon and Canon SLR’s will look far more like the Sony A7 then a SLR. They will go mirror-less. Its a matter of cost. Producing a mirror box and optical viewfinder is expensive and when Nikon and Canon do jump onto this, possibly when the autofocus matches there low end SLR’s it will happen.
Then its going to be difficult to see where Sony, Fuji etc are going to go. I feel Panasonic and Olympus have a better chance of being a long term success, as the smaller micro four thirds cameras can make an excellent second small system