As for the Df...well, that is a bit of a mystery camera. I am not going to hide the fact that I possibly will be in the market for a new digital camera within the next 12 months (wash my mouth out with soap). If and when I buy a digital, I want to ensure that I future proof it as much as I can. I would tend to think that the camera that I buy next will last me a good while. I have looked at it (& even discussed it at length with a sales guy that I know quite well) and the DF brings nothing more to the table. The only thing going for it that I can see is its retro looks and maybe the fact it shares the sensor with a camera that is nearly double its already excessive price.
But there is something else that I feel will mean the end of SLR's and that is the implementation of electronic viewfinders, such as those used by Sony. The more moveable parts that are eliminated, the more efficiencies can be made with both frame rates and reliability. In the end, I see it as a win win for that type of photography. These EVF's are still in their infancy (for high end gear). Give them a few more years and people will be saying "Pentawhat?" (well, except for us on who still like to place pieces of film in the back of their cameras!)
(OK, that's enough for now - I am sure I am on the bubble for getting this thread closed and myself banned).