I think I would send the world down the runway.
There are so many beautiful clothing styles that have been worn by billions of women for thousands of years, with lines of such beauty and elegance that they look good on women of all ages, all sizes.
This is already happening in little drips and drabs. What is the ankle-bunched skinny jean but a modern, "global" take on the ancient churidar pant?
Of course, in its original incarnation, worn under a long kameez, it looks equally good on someone five feet tall who weighs 150 - oh, and who wears flat-heeled shoes with it - an accomplishment that is beyond the intrinsic fashion capacity of the modern skinny jean.
So I would bring fashion back to what it is intended to do, which is make us all look great. Not just those of us who are six feet tall and weigh 110.
And to do that, I don't think it is necessary to re-invent the wheel, just look around us at all the wheels that have already been invented, and see how round they are, how smoothly things move when placed upon them, while their poor re-invented cousins are all lumpy, and will only serve to transport one or two things, and then only when set upon specific roads.
The world, and the history of our species in it, have developed a sumptuous smorgasbord of fashion that exists for no other reason than to make us all look beautiful.
Not to make rich men richer, not to make me or anybody else famous, just celebrate our beauty, and adorn ourselves to enhance and showcase it!