Alberto Tanikawa: Chuck Westfall did not go into too much technical detail on the sensor. 18mpx may not seem enough for some, but what if, a big IF, Canon pulls something like a layered sensor - a la Foveon? Not very likely, but 18mpx like that, great ISO performance, and speed in one package, the 1Dx would be hard to beat!
Foveon's are noisey at anything over 400 iso.
Paul Guba: You know I have been taking pictures for 25 years and have yet to feel the need for 6 digit ISO. Perhaps when I get paid to photo a coal mine. Call me a minority but I would actually like lower ISO, like 32 or 16 I would find it quite useful in studio and with landscapes. That said I shoot nikon and canon and both are fine tools and I don't really give one the edge over the other. I don't have much need for video but it seems that is the biggest thing Canon is offering. Much of the changes are to increase video performance so they must see that as important.
Its not about the camera. Go take pictures.
I agree with both Paul and andreas_d, and totally agree with Paul for the need for a lower ISO. The need for ND filters is really old school.