I think what killed the medium format was not the megapixel count, a D800 is not going to beat the aged 33 or 39 mp backs in control or reasonable light.
That will be easy enough to verify in 2 months from now.
My personal bet is a D800 win along most metrics, but I could be wrong.
I think people's desire to try better camera is still there, and the digital back is still the dream, even though it is not for everyone. I think the digital back sales will be dropped, not sure if price will drop that much. The biggest reason for the high price is the small quantity to cover the cost and R&D, sad truth!
There is nothing unavoidable about this. The current situation is the result of business decisions by the people running the MF companies. Pentax has clearly proven that it is possible to deliver a superior camera at a much lower price point.
Most companies assess the market, understand the value that
needs to be delivered at a given price point and develop accordingly. The clear exception is luxury goods where the price is computed based on an assessement of the
want of potential buyers (high end audio is a relevant example here). It could be argued that the initial pricing of high end digital backs was computed in terms of value relative to film cost savings, but this argument doesn't stand anymore.
We hear hundreds of photographers claim they want to work with MF. I can relate to that, but those guys are not saying that they want to keep paying 40,000 US$ for a new top back every 4 years. Those guys are saying they want to use equipment that gives them a good safety margin relative to their actual needs. The problem is that the D800 does that also for 99% of actual needs and so does the Pentax 645D.
Once photographers realize that these claims are not the result of some brand fan boyism but the result of real world usage, they will get back to Phaseone and Hassy and tell them "guys, I like you, you deliver good products, but so do the other guys. Considering the number of people willing to shoot phaseone, price your top offering at 15,000 US$, the medium level at 10,000 US$ and the entry at 7,000 US$ and you'll make a lot more people happy".
Cheers,
Bernard