... There’s another reason DSLRs are in their twilight, and one slightly more insidious than any of the photographic reasons we’ve discussed above: mirrorless is simply much simpler – and therefore cheaper – to produce, and this of course translates into much better profit margins for manufacturers. ...
... Put it another way: even the most complex of the mirrorless cameras – the OM-D with its 5-axis stabilisation system suspending the sensor – it’s still significantly simpler than the mirror and viewfinder assemblies required for even the cheapest DSLR. I was told by one of the manufacturers that a mirrorless camera has approximately
60-70% fewer parts than a DSLR, and can be produced in significantly less time. Having stripped several Sony NEX-5s for multispectral conversion, I can attest to that: I can strip, remove the UVIR filter pack and reassemble in about fifteen minutes. I tried to do the same to a Nikon D50 once: it took me three hours the second time, partially because of the number of parts, partially because of the testing required during reassembly.