I found it an interesting thread, especially since I spent hours pouring over How to Ski the New French Way when I was a kid. But one problem with it was that it could be hard to follow the discussion because of having to work out the difference between Jet turns, Serpentine etc. I though it might be fun to approach the whole thing from another angle, starting with the clip below of Killy skiing in the trees.
To me, what Killy is doing here looks pretty modern, a lot more so than a lot of the video of skiing from this time. Obviously his feet are a bit closer together than most people would ski today, and he's using a more exaggerated up-down motion, but, especially later in the clip, he is really bending the skis and letting them do the turning, though perhaps more in the second half of the turn--I can see when the snow turns harder, he's using some rotation to initiate the turn. I'm less interested in whether what he is doing is actually serpentine or avalement, than I am in how what he's doing compares to modern skiing.
Btw, I have no axes to grind here, I'm mostly just curious about what people think of this skiing, and beside its a good excuse to share a great clip.