As far as concussions, chronic traumatic encephalopathy (what SI has been writing about) mostly shows up in people who did sports where you're constantly getting 'minor/subclinical concussions' - ie. you get hit pretty much every time you play hockey/football/boxing. In skiing, it seems like you're either not hitting your head at all or getting a full blown concussion - which probably doesn't have the same long term consequences. Nobody really knows tho.
However, given how common meniscus/knee damage is, we're going to be at much greater risk of osteoarthritis. I had part of my medial meniscus removed a while back, which basically guarantees that I'll develop OA sometime in the next 4 decades.