Well, if you're asking why Canon should do an hybrid, then that's because you never tried one or just simply don't need it.
I own a 1DII and a few kg of Canon lenses (from 16mm to 400mm)... Most are L lenses.
But I bought a NEX7 and, man, that's very funny to use.
First : I have it with me everywhere, everyday.
Second : I can use some old jewels I own like the FD L lenses and some Voigtlander... I don't own Leica lenses though. Manual focus with those lenses is a breathe ! Faster than with my F1N !
Third : The image quality is on a par (to say the least) with the 1DII, including in low light !
Fourth : It is silent and so "unobstrusive" you can get pictures you wouldn't get with an SLR.
The EVF is a marvelous thing, after all. Now I want to zoom for focus while looking in the viewfinder of the 1DII... Unfortunately, it doesn't work
OK, so why a Canon ? Because my best "APS-C standard" zoom is the Canon EF 16-35L (realy good on APS-C) and I miss the aperture setting (!), the focus... or just the EXIF informations ! (No to say IS on some lenses)
I guess with a Canon, this should work !
IF Canon can build a small camera with EVF and interchangeable lenses -including a full support of EF(-S)- and a faster AF, with at least an APS-C sensor, this would be a winner, in my opinion ! Isn't Canon market leader for DSLRs ?
I just want to make sure they include "focus peaking", digital focus aid zoom and so on... and, if possible, a short flange-to-sensor distance to allow to use as much lenses as possible !