I am skeptical of those numbers. Like, decades ago 1% needed IVF? I assume that's what you are referring to. Is that not partly a result of it being fairly new technology, quite expensive and not readily available to most people? And the 17% number, while it does seem to be about right, how much of that is just that the average age of parenthood keeps going up and up? It does not seem surprising that the older you get the more problems you have with fertility.

I would be interested to know what the actual rate of sperm count decline is, controlling for age and such.

Edit: This is good reading, I think, though dense: https://pmc.ncbi.nlm.nih.gov/articles/PMC6455044/

Rates are down quite a bit in the last 50 years, about half. But extrapolating to zero in 50 more years is a stretch. Average is something like 40-50 million/mL, which is above the 15 million threshold considered normal, but does mean an increasing number of people are falling below that threshold. So yes there is going to be an impact, extinction seems highly unlikely however.