Looking at the FF DSLR market from an economic perspective, I suspect that even at $3-7K Canon is not making significant profits on its FF models. If Canon were making excess profit (supernormal profits) competitors would have rushed to this market segment to reap these profits with a predictable decline in price to a 'normal' level. If this were a significant market with high profits, we would have expected Sony to make its entry here first, and eventually migrate to the prosumer market. Sony's entry into the 10mp prosumer segment is a strong indicator of profit potential, and it should be no mystery to anyone why Canon and Nikon are not at war over the FF market. The benefit of producing these expensive and rather exotic cameras is much like that of racing to auto manufacturers. That is the development of technology for use in average products and the inestimable marketing benefits.
I am also fascinated at the disappointment of so many photographers that they must wait another year to chuck their existing DSLRs to spend thousands more on a new one! Could someone please explain the terrible deficiencies (other than costs) of the 5D, EOS 1Ds MkII, or the D2x? On the bright side, this bodes well for buyers of used equipment!
Cheers,
Scott