I think this is rather naive, as most of the "End of the DSLR era" commentators are. There is a hell of a lot more to a camera than "a lens that focuses light on a sensor". Of significant note is the ability to preview what your going to be taking a photograph of, and focusing the subject(s). Both of those areas are currently areas where DSLR designs are supremely strong, and mirrorless designs are rather weak. I think it will take a good couple of generations...at least...before mirrorless starts to intrude into the territories that DSLR designs currently cover to near perfection (thanks to the fact that they are ancient, established, and well-proven designs.)
I've tried out a few mirrorless cameras, both with and without optional OVF's. One thing I can say with GUSTO is that EVF's are terrible, for a couple reasons. One, being electronic, they have to transfer information from the sensor to a small screen, which has its own inherent limitations. Despite fairly high refresh rates on the EVF screens, transferring information from the camera's sensor and processing it such that it can be displayed on the EVF takes time, often limiting your frame rate. Even at a frame rate of 30-60fps, EVF's are not immediate-mode devices...there is still a certain amount of lag. Add to that the resolution of EVF's, which is actually rather low, and often involves cycling the full set of pixels between red, green, and blue channels, results in far less than ideal results. For mirrorless cameras that have an attachable OVF, you have parallax issues, AF point selection and AF confirmation issues, etc. At the moment, and for the foreseeable future, mirrorless cameras have a very inferior viewfinder story. As I shoot action most of the time, I'll take a true optical viewfinder that shows me exactly what the lens is projecting in real-time and in full detail every time. No contest there, not yet anyway.
The other area where mirrorless lag DSLRs and need more proving is AF system. SLR designs employ a dedicated, high speed, extremely low-light sensitive sensor capable of nearly instantly detecting phase shift and adjusting lens focus in one step. Even with the advent of FPPD-AF (focal-plane phase-detection AF) built into sensors like Nikon 1 mirrorless or Canon's new 650D hybrid AF sensor, they need a LOT of proving and perfection before they could become an acceptable replacement to the proven track record of dedicated phase shift detection AF sensors. Currently, a mirror assembly is required for a dedicated PS AF unit to function, so I don't see DSLR designs going away any time soon, even as the necessary major strides in FPPD-AF designs and capabilities make leaps and bounds over current first generation ones. Again, as someone who shoots action, I'll take a DSLR mirrored design with optical viewfinder and dedicated AF sensor any day.
Finally, there is the issue of ergonomics. Mirrorless is, as I see it any way, very much a fad. Its part of a larger fad, the fad of miniaturization. There are definitely certain benefits to that...cost and weight being a couple notable ones. However tiny cameras have their definite drawbacks as well. One of the most significant that I believe will prevent many current and long-term DSLR users from switching will be ergonomics. Modern DSLR camera bodies are nearing the pinnacle of ergonomic design. Particularly Canon, I think hand fit and form, button placement, and balance are all reaching a pinnacle, where further significant improvement will be difficult to find since there are few improvements left to be made. The small form factor of mirrorless cameras does not work well with the way I use cameras, and the disproportionate size of longer lenses makes for some odd ergonomics that hinder using current generation mirrorless cameras for what I shoot....birds, BIF, and wildlife. It may be that Canon releases a mirrorless FPPD-AF camera design that uses EF mount lenses in a standard DSLR-sized body...in which case mirrorless would definitely become a more appealing option. But I don't see such a thing in the near future...it doesn't fit with the fad.
Finally, I've said this before, and I'll probably say it again many times. New options don't mean the elimination of old options. New options simply mark further diversification of markets. Film is not dead, and while it may not be as front and center as it was a decade ago, it is still used by a not-insignificant number of consumers. Film, both stills and movie film, is the single largest consumer of silver today, and use of silver in film doesn't seem to have slowed much at all despite the larger digital market today. Similar to film, digital SLR camera designs will never cease, and will probably maintain a larger significant use by consumers than film does today. Mirrorless is just a new option, that will appeal to certain users over and above DSLRs for a variety of reasons. It'll certainly gain market share, and in a decade it may indeed have the larger share (as the average consumer who just wants a good camera is more likely to buy a smaller, easier to handler mirrorless than an entry-level DSLR.) I don't believe the DSLR design will disappear from the market alltogether, not in the next couple of decades at least, and while it may take second place to mirrorless in the future, it will remain a significant option for the long term.
