After living through half a century of fashion, I'm convinced the "defining" style for decade usually comes in the last half of the decade and "bleeds" over into the first few years of the next decade--the defined waist and full skirts of the fifties, the mini-skirted/hippy looks of the sixties, the bell-bottoms/wide-collared shirts of the seventies, the line-backer power suits/Madonna looks of the eighties, the minimalist Calvin Klein/grunge/Doc Martins looks of the ninties, the yoga pant/leggings/rocker looks of the 00s, and so on
From that perspective, I think the '10s will be remembered for highly distressed denim, bootie sandals, cropped skinnies, ankle-strapped flats, asymetrical hemlines, "waterfall" cardigans, "designer" sneakers, ponte-knit pants, inverted bobs and longish, chopped fringes. Anyone sporting three or more of these trends would be set for a "Remember the '10s" party twenty years from now. BUT, it may be harder to put together an outfit since most of these items will be in the landfills instead of thrift shops.