LOL! I think, once the officials have drowned out the speculators, it'd make more sense to comment.

But I remember Thom Hogan once saying(speculating, guessing, or whatever he does) that a 36x24 silicon chip would cost approximately $500 to manufacture(to the manufacturer).

This was way back in the D3s - D3x days when the price difference between those two was a startling 99-100% premium for the D3x(about $5k vs $10K).
And that the topic for discussion back then was that the 24Mp sensor used in the D3x was already a production unit made by Sony!
So even if that sensor cost $500 more than Nikon's D3s sensor .. why the massive price difference .. etc, etc.

2.500 pounds will probably make this camera less of a success than it otherwise could be.
Even if it betters the Df in terms of performance in many ways, the price is still a factor to consider.

The problem with pricing is one of expectation. It's commonly said that mirrorless cameras are the way forward into the future, and that apart from some disadvantages, the biggest advantage(as I see it) is simply the less temperamental nature of the mechanical side of manufacturing them.
They're supposed to be cheaper to produce as well as being more simple .. where the simplicity of manufacture(no miniscule tolerances in mirrors and mechanicals to concern over!) is what makes them cheaper to make.
The the A7s comes in at near the same price as a Df, it smacks of profiteering on the part of Sony, because the expectation is that it supposed to be cheaper than an equivalent type SLR design.

Hopefully the (apparent)success of the A7/A7r hasn't made Sony more arrogant.
(just as successful cameras have made Nikon arrogant )

Y'know that I seriously considered an A7 for a while. Went to the camera shop to confirm the then current internet hype about it, so I could hold it and play with it. Had about 10mins or so to play.
Mounted two different lenses, and the only thing that surprised me was that it was comfortable to hold, against my expectations(smaller camera/grip=less comfort in every day usage for me).
Couldn't get past the EVF tho! .... put that plan to rest.