Amazon would make so much money launching their own, but how many of us would love to see them accept a large number of major cryptos. Just like Visa, Mastercard, American Express doesn't it bode well to give the consumer multiple options? Especially this early in adoption, they could make a killing collecting them now and having them worth XX times in 5 years.
Maybe even launch their own and offer a slight discount on items if paid through AmazonCredits. That way every digital payment consumer wins.