This.
Apart from an irrepressible urge to be full-frame, going from a top level DX to entry level FF does not seem like an 'upgrade'. If anywhere true, this new camera could serve as a backup FF for some pros, or a learning tool for others aspiring to be pros.
It really depends on the price and sensor and features, etc.
If the D600 has features comparable to the D300 and D700, then it's no "entry level" setup. Even if you are "entering" into FX, it will be superior to the D7000 in many regards. I could see the D600 being a "merger" between those two lines, leading to essentially a D700 replacement, while the D800 holds a much higher pricepoint.
Features-wise, I would expect it to be at least comparable to the D300, which is to say it has more features than a D7000.
For example, the D7000 has an "entry level" bracketing mode, limiting you to 3 frames. Most professional HDR shooters swear by 5 or 7 frames, which is very challenging to do on a D7000.
However, on the the D300,700 and D3, D4, etc, you can specify any number of frames (up to 9) with a wide variety of EV compensation values. This is a critical feature for people doing a lot of landscape and HDR work.
The D7000 is also missing a dedicated AF-On button (without losing the AF-L capability) and the DOF preview (without losing the FN button). This is important to many sports shooters and weddings, etc.
It's also missing the more solid all-magnesium body and weather seals of the Dx00 series.
Additionally, the ergonomics of the D7000 are following the consumer-line, with the spinner dial to set exposure modes. I find that it gets flipped out of place quite often while being carried on my hip during a day of shooting, and that sucks! I strongly prefer the D300/D7000/D3/D4 method of using a button combination to change exposure modes.
It's not that the D7000 is bad, but there certainly are features (in addition to the FX sensor) that might be useful to one person or another.
