Right - I think the idea of talent curves is extremely interesting and generally not very well understood. It seems to be the accepted paradigm that to run fast you have to run fast in HS (and college).
I ran D3 and was never even a D3 All-American (11th at track nationals 10k was my best placing). But I got better every year and focused a lot on what I found in my training was working and what wasn't.
Especially in the USA, there seems to be this idea that most runners don't get much better after college, so many of my teammates were really surprised when I continued improving (a fair amount) after graduating.
A lot of that has to do with just training better/smarter (my college coach didn't really have a good understanding of how to train distance runners outside of a very specific type of athlete), but I think a lot of it also just has to do with time and consistency. I really believe that most people's ceilings are MUCH higher than they realize, but so many people get discouraged because they don't see results immediately (or even in a year or two) that they think they've hit their limit.
I've always been interested in finding my own limits and every time that I think I've found them or others are telling me hit my ceiling, I've somehow continued to improve.
Maybe I'm a freak, but I like to think that there are tons of people who are way more "naturally athletic" (my mile PR is 4'29 and I've never broke 59 in the 400m) with much more athletic potential than me.
Anyway, a very interesting conversation - I'll try to check back in on this thread.