I think one thing a lot of industries and companies have regretted is taking on Walmart. Circuit City tried, Toys 'R Us tried and others continue to try. Little 'ole Amazon was sitting very nicely with a great business dealing with parcel delivery in a few days. However, that was not good enough.
They now want to turn their vast and sophisticated network of distribution centers into same day fulfillment centers. There are pros and cons to this and clearly it is a very expensive proposition. Except for the most densely populated areas, same day delivery is cost prohibitive. It is especially prohibitive if you have a normal central distribution point system. Distribution centers like Amazon has are designed to service large service areas - like 250 mile radius and are too big to blanket the Country with them.
Enter Walmart and their "test" of same day delivery.
Walmart sees the Amazon plans and basically says, "I see your same day delivery and I raise you by 4,500 stores / "Distribution Centers". The interesting part of a Walmart store is the consumer sees it as a retail store yet the smart people in Bentonville see them all as distribution centers. Let's say the average radius around a store is 15 miles before you hit another store. Given this (and I am sure the statistic is available.. this is my guess.. not counting the outlands / badlands etc) you can see the advantage Walmart has and will always have over Amazon in same day delivery. This will remain true unless Amazon wants to go on a mind boggling spree of capital investment to build out stores. My bet is if there truly is a market for same day delivery (which is very questionable) then Walmart wins before Amazon even gets on the field.
A lot of people have lost a lot of money betting against Amazon over the years however this endevor may be a "bridge too far" even for Amazon. My advice: Don't take on Walmart. Find the white space between you and Walmart (as Amazon has done so nicely over the years) and dominate that space.
The war of final mile delivery is about to begin!