Digital is a baby, and a remarkable baby at that. But just as film was not the ultimate, I doubt digital is either.
We should not forget that
digital cameras, like modern hi fi sets attached to CD and DVD players, are a mixture of digital and analogue processes. In fact, the most significant part of a digital camera, the digital sensor, is still in large part analogue. (If I've understood the process correctly
)
We have a photosite or photodetector which accumulates an electrical charge
in proportion to the number of photons that have impinged upon it. That's analogue.
As with all analog signals, the accuracy of the match between the signal and what it represents, is degraded by real world interference - in short, noise from whatever source, including noise introduced in the process of converting those millions of different electrical charges to digits.
Now I know you're not so old-fashioned that you don't appreciate the significance of a true digital process . If that picture information could be digitised at the precise moment the photons impinge upon the photodetector, we'd have a true (and perhaps the ultimate) digital camera.
How this could be possible in practical terms, I don't know, but it's not difficult to imagine a small sensor, say 2/3rds", with literally billions of photosites. Instead of accummulating varying degrees of electrical charge subject to severe degradation, each photosite would be in a state of 'on' or 'off' depending on whether or not it had received a specified minimum number of photons, say 6 being the minimum quantity to rise above the noise floor.
Such a system would probably be comprised of 3 sensors, one for each primary colour. The resulting image would consist of nothing but the presence or absence of 3 dots, red, blue and green, which is all you need - a bit like your computer monitor really.
Of course, it goes without saying that current computers couldn't handle all that information. We'll probably have to wait until quantum computers become a reality. Even at the present time, if Canon were to manufacture a full frame 35mm sensor with the same pixel density as the F828 (which I think would be feasible), it would be aprox. a 130MP sensor producing 390MB images in 8 bit and 780MB images in 16 bit.