Isn't their this kind of risk in lots of sports? They haven't seen talent dry up
e.g. Motorsport
In the 70's Formula 1 there were 9 deaths and many more serious injuries. Safety has improved significantly in the last 15 years but there was never a lack of talent in the most dangerous years.
e.g. Boxing
I don't have specific evidence here but in a sport where people punch each other there has to be long term risk and it continues to prove extremely popular.
e.g. Rugby
Again little specific evidence but it's at least as brutal as the NFL and lacks the protection for the players. I know several kids in my local area who have suffered broken necks, paralysis, and I've heard of one death. And these were kids playing for their high school team. Yet it continues to grow in popularity and talent.