Physical stores are still a vital component to retailers' businesses, Target Chief Executive Brian Cornell told CNBC. Over half of Target's digital sales growth is enabled by stores, Cornell explained. That includes shoppers ringing up purchases online before picking them up in person, or shoppers browsing Target's aisles before buying something from Target.com. Target's stores are also increasingly serving as fulfillment centers — 1,400 of them can act in that capacity today. And heading into the holidays, the retailer's stores could support north of 80 percent of online orders, according to Cornell.