Just a simple hypothetical for the start of the week
What would the following cameras be worth to you?
36MP full frame camera with a 28mm f1.8 lens
21MP APS-H camera with a 36mm equiv f1.8 lens
16MP APS-C camera with a 42mm equiv f1.8 lens
9MP m43 camera with a 56mm equiv f1.8 lens
and a 5MP Nikon CX camera with a 75mm equiv f1.8 lens.
Not trying to be deceptive or anything. If you didn't notice, all the above are actually the same camera/lens. I've just done the maths to see what you get with a crop to some standard sensor sizes.
This will be essentially what you get if u paired a D800 with a 28mm f1.8G lens.
As a interchangeable lens DSLR design, a D800 with a 28mm f1.8 lens is considerably bigger than it can be. With a bit of extrapolation one can imagine a hypothetical full frame compact with fixed 28mm f1.8 lens a little bigger than a RX1.
Now the above hypothetical camera will beat most full frames at around 28mm, beat an X100 (which is at 35mm equiv), beat a Sony NEX with Sigma 30/2.8, almost match a m43 with a PanaLeica 25mm f1.4, and beat any Nikon 1 camera with any lens near the portrait focal length (cos Nikon CX's lens selection is currently severely anaemic), although mp drops to 5mp but still useful for holiday snaps which is what Nikon CX is essentially aimed at.
Obviously this camera has limited appeal to the tele shooter.
But it could replace a whole system such as m43 depending on your shooting needs.
It also raises another question. As IQ improves, does cropping (digital zoom) make an acceptable optical zoom replacement. That's Nokia's strategy in their Pureview 808 smartphone. I'm starting to think its not such a bad idea.