I think there is a real question as to
whether Fuji makes any sensors at all
Well, you have to define the word "make." I don't believe Fujifilm has their own fabs. The issue you refer to was a contamination issue, so if Fujifilm purchased materials from the same source or time on the Sony fabs you could explain what happened perfectly well.
and are probably in a similar
providing engineering input role to Sony as Nikon.
The interactions between Japanese companies is insidious and almost impossible to pull apart. Moreover, many Japanese companies feel it is better to share low-level technology so they know and can control what their competitor is doing. They do very poorly when something like a Foveon comes along with a technology they don't have and don't understand; indeed, they'll often attempt to make such disruptive technologies go away.
In addition it
seems to me that other sensor makers would have the same
profitablity problem at low volume.
APS sensors are already low volume. Last year less than 5 million were created. And a Nikon buy of an alternative sensor would essentially drop Sony's volume by more than half and increase a competitors' to larger than Sony's. I think there are plenty of firms that would be interested in such an arrangement, if it could be pulled off.
It seems unlikely that one
company would snag all of Sony's sensor customers.
But that's the thing, they only need to snag Nikon right now. That would give them about a third of the APS sensor market overnight. Canon's portion can't be touched, so that means the remaining players other than Sony have a choice of Sony, who Nikon chose, or some REALLY low volume sensor.
Of course, two years from now, if Sony really establishes themselves as a viable third option and Nikon and Pentax are still using the same sensors as Sony, the game is up, I think.
--
Thom Hogan
author, Nikon Field Guide & Nikon Flash Guide
editor, Nikon DSLR Report
author, Complete Guides: D50, D70, D100, D1 series, D2h, D2x, S2 Pro
http://www.bythom.com