Did he (Killy) ever ski a N.E. lost ski area?
I suppose it's possible that he made a run or two at Mittersill (still open at the time) when he was competing in the World Cup races at Cannon in 1967, though I don't know of anyone who said he did. He was pretty busy with three races at Cannon; slalom, giant slalom and downhill. And he won 'em all.
Speaking of famous skiers and lost areas, how about famous skiers and lost trails. In my youth I once watched an International downhill race on the old Nose Dive. The old Nose Dive is actually a lost classic trail. It got bulldozed back around 1966 or so. When I saw this particular race, it still had all the famous sections: Seven Turns, Corridor, Shambles, and Shambles Corner which was preceeded by the biggest drop on the course. The fast line through Shambles was three feet from the left side of the trail which was marked by large mature sugar maples. No fencing, no crash helmets.
The guys I saw were: Tony Sailer, Buddy Wener, Tom Corcoran, Christian Pravda, Anderl Molterer, Chick Igaya, Brooks Dodge, Betsey Snite, and Penny Pitou. Sailer (three gold medals the year before at Cortina) wore his signature white ski hat, easily recognizable.