I'm sure you are right Theodoros, I'm just passing on what I have been told by Hasselblad, I imagine they are wrong and you are right...
I suspect Theo is right. Sony and its customers need working hi rez sensors for their own many purposes, of which still photography are just a fraction, and in fact some 50 sample files date from 3 years before the chip's adoption and release by Phase. Of course each customer chooses to implement what is desirable for his application, and the electronics for 25 fps 8K are presently well beyond Hassy's internal design capability. It is already amazing they can do raw 4K, and chose to budget delivering this very expensive feature.
One of the reasons I like Hassy these days is that they deliver some cutting edge camera features, like multishot and truefocus and now Raw video, and then actually make them work rather than be gadgets, while Phase concentrate on steady progress, C1, and their dealer network. Basically, Phase are always playing catchup on camera features. Leica have bet on ergonomics and lens quality, and that seems to work for them.
BTW, if one can do it, there is something extraordinary about framegrabs from a movie capture; I've done it with my GH4, and one gets some extraordinary "moments" when an expression or the light are just right. 4K captures are already 8MP, more than enough for web use.
Edmund