Two recent occurrences serve as signals that we’re at a marketing crossroads. In June, Amazon announced that it had offered to buy Whole Foods for $13.7 billion. Two weeks earlier, at Walmart’s 47th Annual Shareholders Meeting, President and CEO Doug McMillon vowed to make the company “people-led and tech-empowered” with enhanced capabilities for online ordering and better delivery options. (Walmart was also rumored to be a potential Whole Foods suitor.) ... Read on.