Many years ago, I have the privilege to study the Zone System, first under Dr. Minor White (at my alma mater, Rochester Institute of Technology), and later from John Sexton (a former student and assistant of Ansel Adams) and Dr. Jerry Uelsmann. Dr. White passed away in 1976, so you can guess how old I am.... now.
Now, let's go back to our discussion. Is the Zone System still relevant in today's digital age? My answer is a big 'YES' of course (you might have already guessed my reply). In fact, if you take a close look at Photoshop, many of its terminologies are derived from sensitometry, in which the Zone System is based on.
Unlike normal folks, when I look at any image I don't look at it in color but in shades of gray instead. Don't get me wrong. The Zone System is applicable to both B&W and color images. Just that I am so used to judging a scene in different zones that my mind's eyes switch to 'grayscale mode' automatically.
Call me a weirdo BUT that is how I work. Since I am a photographer by trade, the Zone System is what I use everyday. It definitely makes my job a lot easier, regardless of whether I am shooting, doing Photoshop or printing in the darkroom.