The retail business is witnessing two potentially game-changing strategies: Retail chain Target is opening smaller stores in urban locations to attract younger customers, betting big on that “flexible-format,” as is apparent from a Manhattan store opening announcement in October. Also diversifying its mix is online retailer Amazon, which plans to expand its grocery business with convenience stores and curbside pickups, according to an October 12 Wall Street Journal report .

Target’s move could turn out to be a brainwave that attracts more than just millennials living in urban America, according to Wharton marketing professor Peter Fader .…