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.