Amazon founder and CEO Jeff Bezos is fond of describing the U.S. retail market as having “room for many winners.” Will this hold true for Walmart and Amazon going forward? Walmart remains unchallenged among traditional physical retailers, but will it topple Amazon on the Web? Or will Amazon continue to be the “Walmart” of online retailers? Alternatively, will Walmart end up enlarging the online retail market space, helping Amazon grow in the process?