1. I agree on the two thumb buttons, although I have been able to do without the AF-On on my D7000. I know that depending on how you shoot, this might be a deal breaker. Im sure there is a lot that I dont know, but Im having a problem seeing why that would be that difficult or expensive to add to the D7000 successor. 2. 8 fps or more. Yes, I know this is a big deal for many. Unless they can reasonably upgrade their technology, not sure how they can make a D7200 or D400 with both 24mp & 8fps. No matter the case, I doubt seriously that Nikon could compete anymore with less than 24mp. Personally, I cant imagine needing more than 24mp that are really good. 3. 51 AF points. I see no reason why this has to be a distinction unless they just want it to be. 4. All magnesium body. Not as sure about the cost of this item.
You might also want to add 2-9 bracketing capability.
My perhaps bigger point is whether Nikon will be able to make a case of differentiation big enough to keep both high-end series of DX cameras in the line. What could be possible if they kept both would be to let each leap frog the other in subsequent releases. But, I think both are in need of an upgrade. I know that the D7000s price has been decreasing with several special kit deals as well. If I remember correctly, the D7000 was out there before the D5100, and now there is a D5200. Has the D300s price been decreasing as well?
I guess speculating is futile, but it does bear on my plans, and I aint getting any younger. I am holding off on several purchases currently.