An online book sales business will not keep any potential e-commerce competitor to Amazon afloat in a time when books are impossible to sell. Textbooks made Amazon, and people still think of Amazon to get them, especially with the death of Half.com
. Besides textbooks, books are not profitable enough to keep anything afloat for very long these days.
And I don't quite understand your point about Sears. Walmart copied Sears and took over US retail by being a discount store, which Sears never was. Sears was not and is not equivalent to eBay because Sears was not the only department store for a number of years while also managing to buy out or sue out of business any and all competitors until competitors had no hopes of survival. Amazon is also not to Walmart as Walmart was to Sears, because Amazon made itself online, while Walmart rules retail, which leads us to today where Amazon is rapidly trying to establish a brick-and-mortar presence and Walmart has completely overhauled their approach to e-commerce because the only competition left for either company is each other. People did hate Sears when Sears became a department store selling discount store quality items at dept. prices, and they stopped going, hence its death. Walmart, despite all the bad press they get about employee treatment and such, is a company that many people love and trust, and this is due to grocery. Many people use Walmart as a grocery store first and foremost, and then pick up assorted household goods and garden supplies while there, and Walmart has proven over the decades to always provide quality at the lowest prices you'll find, grocery or otherwise.
The battle between Walmart and Amazon is something we haven't seen before, because both companies have established loyal bases but come from opposite ends of the retail world, and many people split their shopping between the two.