If manufacturers find it cheaper and easier to make mirrorless, they will abandon DSLRs. But, the interesting thing is that not unlike LPs vs CDs, film is making a comeback (witness Kodak reintroducing both Super 8mm and Ektachrome) or the resurgence of Polaroid cameras -- true Polaroids like the SX70 (though not like the original 669 etc.). But not unlike those developments, maybe DSLRs become the niche market. One question which begs asking: how does the mirrorless revolution affect front and back focus issues since you are focusing directly on the sensor?
Give me mirrors or give me death!
If you had a lens with a large aperture that shifts focus when the aperture is closed for a shot, it would impact focus, but you would gain dof closing down so in some cases no issue...
Canon appear to have allowed their new R series to AF wide open. It is possible that focal shift with aperture change is a design consideration in the lenses, so they are confident there will be no issue...
Nikon close down to aperture value while performing AF to match the release aperture, but stop closing at f/5.6 to give enough light to the sensor pre shutter release when the aperture will then finally close to the shooting value on shutter release... A concern with this approach is they are stealing light from the sensor for AF operation. It is possible although unlikely, they have done this due to lens designs not limited to focal shift freeing the designers to focus on sharpness and other design factors. It is more likely a feature for dof visualisation, but even that reason alone would be strange given the impact on AF...
Lenses are lenses so assuming Nikon are not restricted for any lens reason, we may see either a firmware tweak or new models that do not do this...
Hopefully we will get more clarity on this...
One other consideration is lenses with very soft off axis performance, that may hinder AF at the extreme edges. Easy to live with and not typical of modern lenses...
Other than that, if you are AF sensing at pixel level as per Canon, then it should be very accurate. Reviews of the R seemed impressed with the speed and accuracy, including eye AF which one reviewer has suggested will get a firmware upgrade to continuous mode. Currently one shot only. I expect the next gen Canon R's will have very fast tracking and eye AF. At the moment it would be wishful thinking to expect firmware alone to improve it, but who knows... It does have the fasted full frame AF in any case due to the new RF lens body data exchange. Something that Canons competition will find hard to compete with in the long run...
