Couple of thoughts.

1. Tech prices always fall - Glass I am a bit surprised, the 24-105 is clearly being heavily discounted.
2. Erosion from the bottom up - the "dread" cell phone camera has all but cannibalized the basic P&S market,
3. Sensors are getting better and when 99.9% of photos are shared on the web it is arguable how much "value" is there in the next increment in image capture.
4. Smaller sensors were 1st do to manufacturing issues, perhaps now they are coming back because of image quality that is "good enough," Light gathering etc is being addressed as I have seen recent "Noctagons" for 4/3 being developed and/or speed boosting adapters. Again, 99.9% of the images being for the web/small screen vs. giant wall sized enlargements. (I will stipulated that larger photosites are better photosites)

It isn't any one thing, rather a broad erosion on several fronts. I still think it is a wonderful time to be interested in image capture, etc. as a consumer. Trying to be a manufacturer is something too complex and dynamic for my participation.

A bit off topic, but imagine a super functional little body/sensor w/ a likewise lens wirelessly connected to your google glass "EVF." No more having to bring the camera to your eye kind of stuff. Oh such fun.