Walmart and Amazon have been participating in an apparent game of Tug of War around the lowest threshold for free shipping eligibility for some time now. In February, Amazon lowered its minimum free shipping amount to $35 (2250 around) to match Walmart. Recently, Amazon decreased its pre-declared minimum by $10 and is now allowing free shipping for orders above $25, something Walmart hasn't reacted upon yet.
Although sources confirm that Amazon(.com and not .in) was offering free shipping for its Non-Prime members at $35 until May 2, the exact date of introduction of change in policies could not be pinned.
Walmart made the first move when it offered free shipping on any order(s) of $35 or more. A month later, Amazon hit back by matching the exact price, although it had to come down from the then rate of $49 for free shipping to match Walmart's $35.
Two more months later, Amazon backed up its move by further lowering the price of free shipping on orders. The first price drop wasn't announced officially either which makes the unannounced second drop not much of a surprise.
A year or so ago, Amazon's free shipping rates were $35. It had upped the price to $49 and had to come back at $35 to preserve its consumer base.
While Amazon and Walmart are busy competing for market dominance and consumer base preservation(of their own) and churn(of the other's), it seems that the customer will continue to benefit. As per market economists, as the two primary players in sale keep at war, the prices (and the shipping of course) will keep getting lower. They may also be morphed in a way that benefits the customer, making them richer(since real income will rise with a decreased cost of living, so to speak.)