Yes, indeed... Nikon is probably going to announce a D800 a few months down the road too. It would be a very cheap operation for them really.
With the recession upon us, Nikon will almost certainly have the capacity in the Sendai plant to add a "D800". If the D3x shares the same body as the D3, then practically all they have to do is to put the D3x sensor into the D700 body -- which leads me to think they might call it the "D700x". The Sendai plant would then be producing 4 cameras built on two bodies and two sensors, which sounds like a winning operation to me as they can squeeze down costs on both bodies and sensors.
As far as I am concerned though, the killer feature of the D3/D3x over any other pro body out there is the double CF cards slot in backup mode.
The peace of mind of knowing that even a fried CF card in the middle of a once in a life time shoot is never going to impact me is just great.
It is the most compelling feature for me too. I already find myself often having to change CF cards in the middle of shooting using my D300, since that will happen twice as often if I stick to 4 GB CF cards in a D3x, then I would want dual CF card slots set to seamlessly switch when capacity on the first card is reached. At a $1700 premium though, along with the extra weight I do not want, I would instead prefer a D700.
This being said, I am really not sure whether I'll buy any of these bodies in the first place, the D3 remains a superb camera for landscape work, especially when doing stitching.
My D300 does very nicely too, and the prospect of slightly improved pixels on a larger format is what I really want -- that means half as much stitching. With the DX crop mode, I can also dial back to 10 MP when appropriate. I will likely give my son my D300 and buy a D700 to go with the D3x predecessor for myself; I also have an IR converted D200 and hope to convert my other D200 to true B&W (no CFA or AA filter); that will be all the cameras I need until Nikon comes out with a modularized system that allows me to carry one body and several sensor packs (high ISO, high MP, B&W, etc.) because my bag is getting too heavy and I will find myself leaving half my cameras at home.
I'm very interested in that new OLPF type, and 16 bit quantization. I wonder if it'll be really sharper, and will have increased DR...
Nikon has been using 16 bits in many of their cameras for quite awhile now (as far back as the D2Hs), and since the D50 they have been using it in all their cameras; the D3 and D300 were the first to offer 14 bit files though.
I am wondering what you mean by "increased" sharpness and DR. "Increased" from what? The pixel density of the D3x is about equal to the D200, and I would expect the D3x to have more per pixel acuity than that camera has; after all, my D300 already has greater per pixel acuity than my D200 camera bodies had (the IR converted D200 has no AA filter, so its per pixel acuity is a little more now). As for DR (and by extension higher ISO performance), I would expect the D3x to have slightly more than the D300 but noticeably less than the D3 or D700.
There is also the CFA (color filter array) to consider in the image quality the camera produces. Iliah Borg has converted D3x files, and he wrote that
"...those who want the camera not for formal numbers but for real images will not be disappointed." Iliah Borg also says the native ISO of the D3x is about ISO 70; compared to approximately ISO 130 for the A900 and the D300; I'm not sure what the native ISO for the D3 and D700 are, but
Yves Pinsonneault has
observed better results between ISO 400 and ISO 800 than at "base" ISO.