Street Musician, Ottawa -- Canon 5D & EF 35mm f1.4 @ f1.6, ISO 3200.I think most people are surprised how well the micro 4/3 cameras are selling, possibly including the m4/3 manufacturers. This clearly shows how traditional DSLR manufacturers have been ignoring the market segment where people want small, yet interchangeable lens Digital SLRs. The Four Third format was a good attempt, but unfortunately not very successful, because 4/3 cameras are not much smaller, if at all, than traditional DSLRs, simply because of the optical reflex mirror, which limits how small the camera can get.
By removing the reflex mirror, a lot of restrictions are lifted and many benefits are immediately apparent. These include lower cost, as the reflex mirrors is one of the more expensive components of the body, shorter lens to sensor register (thus making the body thinner), smaller lenses, and best of all, less vibration due to mirror flap, so you can take pictures with slower shutter speeds.
I think the time for a full frame Electronic Viewfinder Interchangeable Camera (EVIL). The megapixel electronic view finder is now almost good enough as a replacement for an Optical View Finder. After using the Panasonic G1, I really prefer an Electronic View Finder for manual focus than an optical one.
Imagine a Canon 12MP 5D without a mirror box. This can be made much cheaper, but have ultra high usable ISO a la D3s. The full frame EVIL will be an entry level camera priced around $1500, will sell like hot cakes. Best yet, make a monochrome version of this camera without the Bayer array, for the B&W fanatics.
The reason I like to have an EVIL full frame, is to have much better compatibilities with manual focus lenses. Right now, so many lenses hit the mirror on my 5D, but if there is no mirror, all those lenses that could not be used because of mirror clearance can now be used. Manual Focus Lens nuts all over the world will rejoice!
Wishful thinking, I know, at least for the foreseeable future. I firmly believe future DSLRs will be mirrorless. We will wait and see.