Upload & Sell: Off
Yes. But not a camera to "upgrade" to for you and me
Not for me, since the 5D2 does beautiful work already for my photography and I don't need the higher speed or beefier (read, "heavier") construction of the 1DX for my work. For those who need such features in their cameras, the 1DX looks like it will be a very fine camera, indeed. (If I needed a new body right now, it would be a 5D3. If I were a Nikon shooter, I would be looking at a D800.)
The whole business about poor low ISO DR performance is largely a forumtographer meme that is almost entirely irrelevant to real photography.
The entire digital photography camera market seems to be firing on all cylinders right now. A bunch of manufacturers are making really excellent cameras, lenses, and other gear - and not just Canon and Nikon at this point. We see very interesting and compelling developments in the rangefinder-style cameras as well, great stuff is happening in the MF format space, and more. Photographers today are more empowered by and less limited by their equipment than at any point in the history of the medium. It is a great time move beyond the forumtographer mode of searching for and fretting about this and that little difference in specs, to select a camera, and get on with the work of making compelling photographs using this gear.