No secret, really. Legacy retailers like Sears, L.L. Bean and Nordstrom are still around thanks to a combination of great customer service, solid core values, and/or a willingness to change with the times.
"There are a variety of reasons why a retailer may last for decades, even centuries In 1911, Leon Leonwood ("L.L.") Bean came home from a hunting trip frustrated by how cold and wet his feet had got trudging in the woods."