<<So perhaps you could elaborate on the reasons for your scepticism about the D800 not performing adequately as an APS-C camera>>
I have both a D7000 and D700 and it may be that a D800 will combine the best of both worlds. I enjoy 2 genres, landscape (D700) and wildlife especially birds in flight etc (D7000). I really have not been persuaded yet that there is anything that a D800 will do for me that a D700 doesn't at present. As I don't print larger than 16ins x 12 ins very often the D700 suits me fine, so a D800 is not going to fix something that isn't broken! The D700 is a fine camera that even offers DX crop mode, however the resultant file sizes are only about 5Mp, far to small for enlargements. This is where DX mode on the D800 interests me. The DX mode will supply adequate file sizes for my printing needs.
For numerous reasons I won't elaborate on here, I find the D7000 doesn't suit me and am eagerly awaiting a D300s replacement. Whether or not this becomes a reality will possibly become apparent next month at the "Photokina" event where undoubtedly new Nikon products will be announced. If no D300s replacement is announced I shall see it as a clear signal that Nikon are probably not going to produce a new semi pro body in the future. If the replacement doesn't materialise the D800 becomes more attractive as I could sell my D700 and keep my D7000 as a spare body.
Finally, from a financial point of view a I hope any new DX semi pro will be better priced than the D800. I really wish that Nikon had not launched the D800, even more so because they haven't launched a new DX semi pro! If the D800 is my only option, I will be disappointed and feel let down by Nikon, for not launching a dedicated semi pro wildlife and sports camera to accommodate the need for a small sensor camera with increased frames per second. I know many others will be disappointed too.