Another thing I find interesting is that Amazon's main business is so common that there's a single word for it: retail. They're just yet another middleman between distributors and consumers. Not long ago, a lot of the business world thought Walmart was the indisputable retail king. Amazon proved there's still room for growth in retail.

Will this simple thing called retail produce yet more trillion dollar companies, or is it running out of gas? Will there be an Amazon killer? History suggests yes.