NPR discusses the evolution of big box stores in the 60s, such as Target, Wal-Mart, and KMart. Back then the laws on discounts had recently been loosened, and enabled these large stores to pop up in suburbs everywhere with every family owning a car.
Nowadays shopping is going through a new revolution – the internet. Ironically, stores are now shrinking because of this. Large, non-perishable objects such as technology are being bought online while most people only go out for toiletries and food. While these larger stores may act as a showroom, it’s the smaller stores that are going to catch the niche markets.

This brings attention to the lifespan of such large companies. How long can we expect Wal Mart to stick around? Very rarely do companies like these last for more than a century. What will giants like Apple, Amazon, Microsoft or Google look like in 50 years? What will make them go into decline if they fall? It certainly is hard to remain at the top.

http://www.npr.org/2012/11/19/165295840/the-past-and-future-of-americas-biggest-retailers