A better CMOS sensor would certainly solve a momentary gap, but the reason is more based on the economic and maker side.
As Cameras today MUST become fully electronic to fulfill the features wanted by the customers to fully utilize their digital systems
(e.g. conncetivity with either highspeed local wire - or wireless networks, internet access,precise Video preview, compactnesss and reasonable price)
the numbers of the systems must be improved by doing a programmable , universal, standardized and modular platform, that can be produced economically.
The mechanistic, small numbers with customizations done by individual modifications model will not work anymore,only very few will be able to pay for such systems
(30000 € and up) even then these need to use electronics and software, the smaller numbers will make these even more expensive and the price MUST rise further
until even the highend customers will rethink their buying decision and the gap between R&D and the catchup to the semipro industrial cameras will make the
race and even a try obsolete.
This is not so much about MPix, the whole workflow and the integration into a computerized customerbase will do the most pressure.
Phase/Leaf and Hasselblad are doing their own software to keep control of the image devellopment and distribution stage, but this will become more and more complex
and demanding in the future, this part alone is very costly and a real task to solve for such comparably small companies.
Highend customers alone cannot generate the necessary turnaround for all these activities- means they need products that go into a broader distribution channel
which in return means that their exclusive dealership models get into questioning.
Then the lenses: Highend lenses for MF in low numbers will also become a luxury, making it even more problematic to get the necessary turnaround.
There is more , but these are the most important facts.