Any pro knows that most of our work does not require more than 18MP
So very strange - i've been a professional for over 16 years, and i would say the opposite!
My guess would be that most professionals have 1 or two "35mm" bodies. I would say that most photographers take nearly all of the jobs that are offered to them. And, very importantly, i would say that most of their clients do not fully realise what they're after until they get the images in front of their noses. For example, sometimes they ask you to shoot portrait, and then after the shoot it turns out that they'll use the image landscape. Sure, if everything goes to plan (composition, brief, exposure, layout not changing etc etc) then your 18 mpx will be fine ... but as professionals we're paid to solve people's problems, and often those problems come after the shoot. (Many times when shooting with my 1ds III, i've wished for bigger files, so as i can give a client a "post shoot" alternative.)
If i'm right about most photographers clients / needs, then this camera is not the one that they should save for, and have in their bag. And, if Canon do as they say, it will sadly be the only "professional' grade Canon camera.
Personally, i don't want something similar to the 5d. It's not rugged enough, the AF is not good enough (when my mortgage is at stake) - in short it is not "professional' enough.
According to Canon, Moore's Law is dead ... but i bet Nikon don't think that.
I moved over from Nikon to Canon because i wanted a replacement to the d1x ... it would be ironic if i went back to canon because of the 1dx.