Yes, I get that one. My thinking is that the biggest issue is not becoming slower directly, but becoming slower because of reduced traing because of increased injury rates.
I think you've nailed it. The survivors are those who best manage their injuries (which most sports people have).
NB. I found some old fun run certificates this week. There was a time when l was consistently running 10k in around 52 mins. But that was BKI - before knee injury (badly dislocated knee from falling in downhill skiing and my bindings not releasing in time), which l manage but which never really gets better, and squashed discs in my back.
I only once did a 10k time trial. One lunchtime round the old cinder track near work. Potholes and all. I think Craig and I were each trying to run our first sub 40. I was running by myself and managed just under 42. I think that was my peak and its been downhill ever since. Today it was quite over 60 minutes for 10k. Craig meanwhile has gone in the other direction. In retrospect it would have been good to have tried it with other runners to push me.
What is Craig in? He's amazing!