A:Answer First of all, we are in the 21st century - in case you missed it. Specifically, 2019. Companies don't build "replaceable" battery things. They want you to buy the stuff again once the battery is dead. Second, chances are the battery will outlast the headphone itself because the material the headphone is made of will degrade sooner.
Now onto the fun part. "How many hours of use can I expect before it no longer holds a 1 hour charge". I can see science is not your strongest side. If the max number of hours you can get out of it is about 20 hours (with NC on), then how many hours do you think you can listen to (out of the 20) before the battery holds not more than 1 hour of charge? See, this is why you need to pay attention in school as opposed to playing with your iPhone. I could tell you the answer but it involves multivariable calculus, binomial theory, and the Plank Constant, and judging by the question, I think it will be over your head a little...
