Free Shipping: A competitive advantage in the market place?

As the eCommerce world continues to grow and more and more consumers order their Holiday gifts online the question arises, how do retailers gain a competitive advantage? Last year the competitive advantage was offering free shipping. This year, free shipping is a necessity for retailers or they will be at a significant disadvantage. BlackFriday.com reports that Target is going to offer free shipping with no minimum in an attempt to gain more of market share. They did this same practice a year ago as they try to compete with Amazon and Walmart. BestBuy.com is also going to offer free shipping with no minimums this holiday season. Last year they required buyers to spend $35 minimums, showing the market continues to get more and more competitive online. 
With BestBuy and Target offering free shipping with no minimums, the question is what will Walmart and Amazon do? These two monsters in the eCommerce world have yet to offer free shipping with no minimums. Amazon offers it's Prime Members free shipping on all products but last year required free shipping over $35 for non prime members and I don't expect that to change this year. Walmart last year offered free shipping over $50, putting them at the most expensive of the big four online retailers. 
As consumers continue to order more volume online over the holiday season, the big retailers are going to need to look for advantages to utilizing their services.  What is the next approach this year as a competitive advantage? 
Free Returns? 
“While Target has not yet made an official announcement, it appears as though they will indeed offer free shipping and returns from November 1 through December 25 for every single order, regardless of the amount,” BestBlackFriday.com wrote in a post. “This includes standard shipping to 48 (excludes Alaska and Hawaii) states and it may exclude oversized items.” Returns may be another advantage for these big retailers. Amazon Prime members get free returns on most items now. 
Don't Sleep on Jet.com
Another player in the marketplace is Jet.com. Jet's pricing has been tremendous and is less expensive than Amazon but the speed of delivery has been poor and they have had kinks along the way. They are working hard to gain more customers with their strong google advertising. 
AdGooroo, a search marketing firm, found Jet.com led the pack among retailers hustling for clicks, from the top 2,892 Halloween costume-related keywords the firm tracked in August and September with 17.4 percent PLA click share. The start-up has managed to increase its click share on those keywords to 19.4 percent between October 1 and 23. Pretty impressive for a company that launched in July. They're likely here to stay and be a big player.