As someone who is a non-standard size, I hope that new business models provide a much greater range of clothing sizes. Offering three or four sizes of T-shirts is profoundly ridiculous. They will only fit a small percentage of people well. I look forward to the day when you enter your height, neck, chest and waist measurement, specify your desired style of fit (slim/casual/loose) and they find the closest out of (perhaps) 20 sizes and send it to you.
As a thin, tall person, it's virtually impossible to buy clothes that fit properly (even T-shirts). If someone provided a way to buy custom fit essentials, or even just a granular range of sizes, at internet-margin prices, I would sign up tomorrow.