The Computational Photographer wrote The DSLR will probably die. Are mirrorless the future of large standalone cameras?.
Letâ€™s see why I think the reflex design is doomed, even though it has dominated serious photography for decades.
The DSLR has to die because the mirror is too high a cost for its diminishing benefits. The mirror adds to the complexity of the camera and its manufacturing, it makes the camera bigger, and it introduces challenges for lens design. And its advantages donâ€™t extend to video, which is an increasingly important usage case.
Furthermore, the mirror in DSLR severely constrains the design of lenses, by preventing lens elements to be placed near the sensor.
This goes in the same way as what I wrote in September in The future is mirrorless. The reflex design was addressing a constraint to be able provide a through-the-lens view which is now provided using the current sensor technology.