Thom doesn't see dSLRs going the way of the dodo. Cameras of all types have their uses, and niches. As mirrorless establishes a larger foothold in the dwindling camera market, the dSLR will become, in Thom's words:
Many FF 35mm photographers stepping down to smaller sensors notice that lens parity doesn't exist. A m43 sensor attached to a 150mm f/2,8 lens may achieve a similar angle of view as a FF 300mm lens, but its DOF will be closer to a hypothetical and compact 300mm f/5,6 lens.
Size advantages exist only when taking DOF out of the picture. In Thom's words:
I'm assuming that by 16-105mm, Thom is referring to 35mm FF equivalent focal lengths, as 16mm on 1", on m43, on APS-C frames quite different images. Extrapolating on the above, lenses for smaller sensors returning FF-equivalent framing and DOF to a 300mm f/2,8 would be just as large, if not larger, than the lens they were designed to emulate. Which is why compromises exist.
All systems are limited by two pillars: size and performance. Small-sensor mirrorless cameras have certain advantages. Equating FF DOF and angles of view limit much of their utility and every size advantage they boast. And yet, dSLRs grew up to be beasts. Even Nikon's compact D5000 is a beast next to a typical film-era SLR.
Which is one reason Thom concludes thusly: