Faster, Millennials, Kill! Kill!

Burn it all down!

Warehouse clubs such as Costco, Sam's Club and BJ's Wholesale Club have for decades been an American staple: a place where families can stock up on bulk items, try free samples and spend the better part of a weekend morning meandering through aisles filled with 26-packs of canned salmon and king-size mattresses. But as more of Americans' buying shifts online, some retail analysts say warehouse clubs may largely be left behind.

"The core club customer is older: It's generally someone with a family and a house," said Sucharita Mulpuru, an analyst at the research firm Forrester. "Costco has been one of the least digitally forward companies out there. This segment has had its head in the sand when it comes to competing with Amazon."