Increasing portion is not the same as 100%... Vocals still needs to be recorded.. most pple are not keen to hear voices generated by a computer, esp. one that mimics a real singer. They would prefer to hear the real person singing instead. If you need to use a mic, its analog.
Anyway, this digital vs analog thing is real meaningless and pple in this forum are unable to comprehend what is digital and analog and its differences/similarity...
I will just say this.... If your sampling frequency approaches infinity, you will have a perfect analog wave.
Or you can argue by saying that time is quantised and nothing can be smaller than planck scale... So, time moves at min of 1 planck sec. So, everything is digital since this is your max possible sampling rate.
So, i will also say how well you can record sound is limited by equipment and technology. It is entirely possible to record sound and store the wave pattern onto a medium with extremely tiny losses and without converting it into "digital". It will be even better than any digital format. Its is very costly and difficult but not impossible.