Anna Wintour rarely gives public commentary on fashion; instead, she lets her magazine do the talking. But in January, when the American Vogue editor was asked at a VIP lunch event in Melbourne for the Australian Open to predict what would define style in 2019, she obliged, uttering four words: "Sneakers. And more sneakers."

That pronouncement raised a few eyebrows, particularly from those high-heeled attendees who follow catwalk trends closely.