Well,I wouldn't care much at all about 50MP CMOS with an area of 44 x 33mm - Leica S, OK, has the lenses for that but Hasselblad and Phase One don't. It's going backwards in sensor size, which has actually increased to over 50mm (even the old ZD22 was 37 x 49mm).
Generally, you don't need 50MP for portraits and stuff where the smaller sensor is OK. You need 50MP for architecture, landscape, commercial and for these fields you need good wide-angle optics.
For me, the A7R is 'medium format'. We've done our three years of using four different medium format cameras. Even my professional friend and Phase One advocate Kenny Martin is selling his Phase One. His staff may still work with them but perhaps not for long. He's sure he can do everything he needs now on Nikon D800 (etc).