For me, the D700 is the camera I have been waiting for all my life. However, for many a DX camera is a far better choice. For someone doing sports or wild-life photography it is like having a built-in 1.5× teleconverter with none of the downside. For those not accustomed to being a beast of burden, lenses for the DX sensors are lighter, more compact and cheaper. For those who shoot mainly in daylight or with flash as the primary light source, the extraordinary high ISO performance of the sensor is not needed, thus the DX sensor is a money-saver.
Going FX, my bag grew dramatically from a 12-24mm and 18-200mm plus D300 body to a D700 plus 14-24mm huge, heavy and expensive lens, plus the 24-120mm walkin'-'round, shootin'-stuff lens and the wonderful 70-300mm tele-zoom. For me it was worth it, but I rarely carry the whole arsenal, taking only what I think I will need for the shoot. All too often the 14-24mm stays home, and to a lesser extent the 70-300mm. If only the 14-24mm were an f/4.5-5.6 weighing a third of what it does, small and discrete. It is an awesome gold-ring lens, but I would trade it in a second for a smaller, slower lens of equal quality.
I also have a number of AI-S lenses of very high quality that work perfectly but are only used for contemplative photography, which is a small percentage of what I do. As much as I am in awe of what the D700 does, I would hesitate to suggest that FX is the future of digital photography. For me, it has opened up the night and many other things and it is my ideal camera. I would not be so arrogant as to say it is the ideal camera for everyone. DX and µ4/3 certainly have their place and for many, they may be the ideal.
If you are looking for a new camera, don't listen to us. Instead, clearly define your photographic - not cameras as jewelery -goals and consider all the largess that is being announced during the run-up to Photokina plus the wealth of cameras and lenses now on the shelves. Fit the cameras and lenses to your budget and image-making goals, not the quest for the ultimate camera that may be totally wrong for your goals as a photographer.