nikon's giant stride on the march to 'mirrorless cameras'

Recently I saw a camera forum topic entitled 'is the future mirrorless?'

For some time there has been changes to the enthusiast and professional photography market which is still dominated by 'DSLRs' which use a mirror or prism.

All new 'DSLR' systems now allow dispensing with the mirror (or Prism) for some photographs, and some of systems now do not even include a mirror or prism in the camera at all! The change to eliminate the mirror mechanism all together is often refereed to as mirrorless.

Dispensing with the mirror brings the following changes and advantages.
1) Removes a complex mechanical system, allowing smaller and ideally simpler cameras
2) Allows use of a screen to frame photos
3) Prohibits use of an optical viewfinder, forcing use of a screen or electronic viewfinder
4) Requires a new focusing system
5) Allows capture of video images
6) Allows for higher speed frame rates when capturing multiple images

Points 2 and 5 can be provided by simply not using the mirror in when these features are desired, and this has proved so compelling that all DSLRs have now added this capability.

Point (6) has so far been a potential benefit, not yet realised.
Whilst points (1) is a clear benefit of going further and actually removing the mirror mechanism, points (3) and (4) have been so far seen as counterbalancing negatives, as there have been limitations to electronic view finders and new focusing systems.

Whilst for some uses it can already be argued that new focusing systems are actually an improvement, Nikon has recently released the 1 series, which so far represents a significant step forward in new focussing systems. For the first time, one of the two largest DSLR companies, is claiming best auto focusing results without the mirror. At the same time, Nikon has started to realise point (6), faster frame rates.

This further changes the equation of when a mirror system will be preferred. As this system new auto focus system is introduced in Nikon DSLRs, using the mirror will change.

Pre new auto-focus system:
Use mirror if : using optical view finder or requiring best focus system
Do not use mirror if: taking video footage or using screen to frame photos

Now, with new Nikon technology:
Use mirror if: requiring optical viewfinder
Do not use mirror for: best auto-focus technology, fastest frame rate, shooting video, using electronic live image for framing

Clearly, the cases for using the mirror are dramatically reduced. Whilst impact of this new technology is yet to be experienced in a DSLR, it is clear that the occasions the mirror is used will significantly be reduced, and the case for the final step of removing the mirror altogether will be compelling for a larger percentage of camera buyers.

In fact, if most photos are now taken without the using the mirror, cameras will either need to add an electronic viewfinder in addition to the optical viewfinder for any photographer who prefers a viewfinder and desires optimum auto focus results. The case for keeping the mirror, and the optical viewfinder will become increasingly weak, particularly in cameras which have very good low light capabilities and can therefore deliver best results through an electronic viewfinder.