Reuters is reporting that Amazon.com (AMZN -0.33%) may be expanding its AmazonFresh service, which delivers fresh groceries in the Seattle area with its own fleet of trucks. Allegedly, after five years of perfecting the service, Amazon is planning to enter Los Angeles and San Francisco by year-end and will eventually make its way into 20 markets. With Amazon's scale and logistical expertise, it's the type of company that could potentially disrupt the $568 billion U.S. grocery industry. In this video, Fool contributor Steve Heller weighs in on what it could mean for Amazon investors and what it could mean for Costco (COST 0.23%).