Originally posted by Clinton Sure, as long as it is fully supported, and has autofocus capability. Keep in mind, that AF motor is going to have to go somewhere.
And when all is said and done, your camera isn't actually going to be any thinner than it is now.
I find this whole notion is preposterous. First, why buy Pentax if not for the K mount and support. Second, If this were Nikon, would everyone be sitting around thinking how great it would be if they threw away all the glass they owned. For Pentax we shoot with better glass than Nikon; glass that so many of you are suggesting we toss and replace.
I really doubt that it is possible to make a mirrorless FF K-mount camera with full support of old K-mount lenses.
For one thing the camera then has to use phase detect AF, so the camera either has to use a mirror for separate AF-sensors, or a image sensor with PDAF support. But I don't think there will be any FF sensor with PDAF support in the near future (if ever).
Maybe it would be possible for Pentax to buy a custom designed FF sensor with PDAF support, but then the price will very high and it will probably double the production cost of the camera.
If using a new mount it is possible to use contrast detect AF in the camera and put the support of old PDAF lenses in the adapter, just like Sony did on the SLT adapter for NEX, but Pentax need to add a motor for support of screw-drive lenses.
Pentax can then make a small FF camera and it will probably not be more expensive than a similar specified camera from any other brand.
If Pentax keep on using K-mount on mirrorless system they will only be able to sell it to an ever shrinking Pentax K-mount user base. Introducing mirrorless cameras are usually done to expand into new markets, not to support already existing markets. For us who want to keep using K-mount lenses Pentax will continue producing cameras with mirrors.
But anyway, as Pentax has not yet started developing any mirrorless FF system, it probably will take at least 3 years before it can hit the market (if ever).