Walmart currently operates nearly 5,000 stores in the U.S. And there’s a Walmart within 10 miles of 90% of the population. The retail giant has a massive brick-and-mortar footprint—but the company’s dependence on those stores as its chief money-maker might be changing. More of Walmart’s future profitability is likely to come from its sales of ads on Walmart.com and from fees it collects from merchants using its online marketplace and delivery services, than from sales of merchandise at its 10,000 stores, its chief financial officer said on Tuesday.