Once again, it's baffling that there isn't more demand for 50+MP cameras.
How well do Phase One cameras sell?
Given that back in the day virtually all "serious" photographers shot not only 120 but 4x5 (or larger), not nearly as well as affordable medium format gear could.
Canon has had some luck branching out into "cinema" and is attempting to branch out into security cameras. The super-high-end might be the market to pursue.
It's actually surprising how well the D800 does when compared to a high end medium format camera, considering how heavily the specs are stacked against it.http://www.cameralabs.com/reviews/Nikon_D800/Nikon_D800_vs_Phase_One_medium_format_quality.shtml
I also found this kind of funny.
the IQ180 digital back’s new memory card interface is so fast that it eliminates buffering delays, supporting continuous shooting - at 0.7fps - until a card is full. http://www.photographyblog.com/news/phase_one_iq180_iq160_and_iq140
When I first read about the price drop on the Pentax 645D I actually took a semi-serious look at it, but even after the price drop, it can't use Canon glass, it shoots at 1.1FPS, and the IQ isn't a big enough jump above what high resolution 35mm sensors can do. I'm not going to get a $7,000 body just for a mild improvement in IQ at a handful of focal lengths. If a high resolution 35mm sensor only cost a few hundred dollars more though, it becomes an obvious choice. Plus if they let you shoot in an APS-C mode with a higher burst rate you would have an incredibly versatile camera.
It will be interesting to see how well the A7R works hand-held - as anyone who has used or read about the D800 knows, all those megapixels make any imperfections in your technique (and lenses) glaringly obvious. I suspect that the A7 works better for such use. Both would have benefited from IBIS.
The number of megapixels make no difference if you print at the same size.
Maybe not, but a selling point of high MP sensors is the heavy cropping they allow (and, relatedly, the remarkable amounts of detail you can see when the image on a large monitor).
Remember that most crop sensors have far higher pixel density than the A7R, and people have been using those, handheld, to shoot birds in flight for years now. The necessary adjustments to get improved handheld images with a 36MP sensor isn't even going to be half what people do to get good BIF shots.