This is the point where things begin to look really scary for every retail company not named Amazon. Amazon's previous two decades of tiny profits have all been in service of building a massive logistics infrastructure (and locked-in customer base, via Prime) that no one else can touch, and now it's paying off. It's going to be very difficult to catch up to them - even if someone was willing to spend a lot of money to do it, Amazon could easily go back to the old regime of just reinvesting more into its operations; with these last three quarters, they've shown the naysayers that it can be made to pay dividends, and so I think Wall Street would be patient if they returned to that route.