As a wildlife photographer I shoot primarily from ISO 800 through ISO 6400. It would be a great camera if it could hold up with high ISO, but I doubt it will.
I don't. Noise performance is a function of technology, total sensor surface area, and then, to a much smaller degree than the first two, pixel size. It may be slightly worse than the 5D3 or 1Dx, but will be next to them, not next to the APS-C bodies.
This camera will likely be a beast at ISO 100-400 and have an expanded DR which is perfect for landscapes and studio.
DR on the other hand is directly related to pixel size, so a 46 MP sensor will do worse all other things being equal. 16-bit is a marketing gimmick if they can't actually get that much data out of each pixel. If they've worked around Sony's patent, then expect great DR despite the pixel density. If not, then expect slightly worse DR then their current FF sensors.
While I agree it would be nice to be able to crop and still have a ton of pixels (like a crop sensor 7D), the part that will likely disappoint here is that it will have the same IQ as a 7D... which quite frankly is not that good.
The 7D has excellent image quality, pretty much equivalent to the 5D2 through ISO 800. If you've ever stitched 3 frames from a 7D, you want a 46 MP FF sensor even with Canon's current technology (as opposed to Sony's).