Amazon's Retail Dominance

Amazon is a retailer - there are already millions of competitors - you just have to start buying from them.

Amazon now is something like a fusion of Ebay and Walmart. Either of those enterprises (or Target or etc) could move into the full space that Amazon operates in, it seems like.Edit: I suspect that what keeps an enterprise like Walmart or Costco from jumping into full competition with Amazon is that each of these enterprises wants to fish some high profit zone of the eComerce ocean while Amazon wants to be the ocean.

Consider how many competitors went out of business due to Amazon competiton

Amazon fails to eat other companies lunch more often than it succeeds in fact.See: search, auctions, classified ads, smart phones, etc.

Does Amazon really operate on a larger scale than Walmart?

who can compete with amazon when their pricing is a result of their massive scale and supply chain dominance?

I think Amazon needs at least 2 real competitors.

Yes.(1) Yes, I know that Amazon sells some millions or some such different products, but my experience shopping (recently moved and have done a LOT of shopping) is that the company making the product can have a good enough Web site that shows much wider range of products, e.g., for wool blankets many more colors and patterns.(2) To me the key to Amazon is their quite well done Web site that makes it easy (a) to find products and (b) to get relatively good information about them. But can

"Amazon has a win here compared to facebook or amazon"?

Probably due to Amazon's market share inertia, and the high barrier to entry to being able to warehouse and ship a lot of items very fast.