A new separates dynamic?

There are multiple variables that can change in fashion as part of a trend: proportion, volume, pattern, color, skirt length, waist location, etc. But there's one variable I'm interested in but never hear discussed (probably because it changes so rarely) and don't know the name for, and that's the relationship between the various articles of clothing.

Even though I haven't heard a name for this variable, I am sure it exists because it has been very active and changeable recently. Here's the progression we've seen over the past few years in the relationship between women's sportswear tops and bottoms:

1. bootcut pants with tank tops and jackets
2. low-rise bootcut pants with fancy tops and jackets
3. designer low-rise jeans with fancy tops
4. skinny designer low-rise jeans with fancy tops
5. tunics, wide-leg pants
6. tops with leggings
7. dresses with leggings
8. dresses
9. bubble dresses
10. high-waisted jeans

This is probably a little inaccurate, but still -- it's quite a progression! From mid-rise bootcut pants to high-waisted skinny jeans and dresses? What is going on?! It's like there was a whole reimagining of the proper clothing for the torso (from tight and short to long and loose) and the legs (from long and high to tight and low and back again!) and the combination of the two. It was as if the women's top got longer and fancier, becoming like a dress that was worn over pants, until it became long enough to actually go over pants, then pants were eliminated and the dress took over, then evolved its own kind of "pants" (leggings) to go under it, which then grew more important than the dress...

The recent reorientation of the relationship between legwear and...torsowear (?) is similar to what happened during the sixties with the miniskirt. As Thomas Hine points out in The Great Funk, pantyhose came on the market just as miniskirts were surging in popularity. This invention arrived right on time, as pantyhose tempered the miniskirt's shock appeal by cushioning the visual impact of so much leg. Hine agrees that, just like it seems leggings have recently supplanted trousers, "it may be that pantyhose were themselves pants in disguise."

I think it's interesting to take a look at how we put our clothing together and realize how arbitrary it is. We take for granted that men, for instance, wear some kind of pants on their legs and some kind of shirt on their torsos. But this is far from how men used to dress in the past! Men used to wear stockings with little pantaloons and cropped jackets with tails; women used to wear dresses that were actually in two parts; women's sleeves used to be separate from the rest of their clothes; men's ties used to actually hold the collar tight, and their belts used to actually hold their pants up. Native American men traditionally didn't wear pants -- they mostly wore breechcloths, sometimes with leggings that hung from their belts, so that the total effect was somewhat like pants, but was actually put together very differently. Men in ancient Greece and Rome wore chitons, which were not pants at all but more like big loose dresses; men in ancient Egypt wore kilts, which were linen skirts.

All I'm saying is that our basic vocabulary of pants, shirts, and jackets for men and pants/skirts and tops or dresses for women is not the only option. Men and women could instead both wear some kind of dress; or we could both wear unitards; or men could wear skirts and women could be the default pants-wearers.

I'm wondering whether women's separates will keep moving around like they have been, or find one place and stay there. I'm also wondering when the next total paradigm shift will occur in how we wear separates, and what form it will take. One option I think would be really cool, and possible given current trends, would be if undergarments actually became the basic garments, much like the breechcloth was the basic garment for Native American men, and for the other separates to be layered on top of those as needed. For instance, women could wear underwear only in hot weather, a top added as it got cooler, then, as it got progressively cooler, socks, gloves, sweaters, warm thigh-high stockings, boots, and finally a coat. But a woman would still be decent so long as she had her underwear on--her underwear and her shoes.