Regarding the size of the Contax T3... When I've argued with people about this before, some have stated that whereas light can strike film from almost any angle and still properly expose it, a digital sensor requires the light to hit it rather perpendicularly.
Therefore, the tiny lens on the T3 is supposedly impossible at least with current technology. Which I guess explains the huge lens on the Sony RX1.
However, in only a few years time we have gone from almost no large sensor compact cameras to a veritable plethora of models to chose from.
My guess is that the technology exists or will soon exist to make very small FF and APS compact cameras with retractible or very small lenses. What remains to be seen is at what pace the camera companies will release these cameras to us.