Earlier quoted context omitted.
Can you expand on this ominous prediction? What are your experiences?
I used to be able to ride a bicycle for hours on end in my 20's and 30's. Now I can't look up when bent over in that position, I need a rise in the handlebars to get me almost vertical. I didn't hurt myself. I didn't get in an accident. It is just a fundamentally unnatural position and the discs just started to deteriorate from years of holding that position. My bikes were sized and fit properly, and I was doing ever…
The articulation to look up/down is maybe +/- 15 degrees, and being dynamic it should be a positive movement that strengthens your neck.
That you have reduced neck flexibility decades later could easily just be age…