The biggest threat to supermarkets today is not wholesale clubs, category killers or factory outlets. It's video dial tone. Retailers should quake at the idea that armchair shoppers could order anything from arugula to zirconia by pushing a few buttons on a TV remote control. Once interactive technologies turn the average American family room into a couch-based shopping mall, American Express might as well change its slogan to "Don't Stay Home Without It."
If grocery retailers are to