Pardon a well-worn analogy, but 35mm film SLR's never matched medium format SLR's for image resolution (in digital newspeak, "pixel count"); the smaller format built and held its rather substantial place in the film camera market on advantages on other respects like lower size, weight and cost. I expect the same for mainstream DSLR formats (from DX to EF-S to 4/3) relative to the larger, high end formats, 24x36mm and up.
One more US$3000-8000 (your guess!) DLSR in 24x36mm format, this time from Sony, is not going to have any significant effect on the market for distinctly smaller formats like 4/3, EF-S or DX: my guess is that both market sectors will continue to grow healthily. The D300, E-3 and 40D all testify to the vigor of the smaller DSLR formats, 5D and D3 notwithstanding.
(I will not say much about my guess that very few SLR users will ever get much benefit from more than 20MP, or perhaps even much more than 10MP: our eyes are not get sharper with the passing of time, or the walls of our homes much bigger.)