Since paypal is basically ebay owned and not accepted at amazon it does make sense they might incorporate a crypto as a way to attack paypal. Maybe they will launch amazon coin we will see.
Paypal and Ebay are two separate companies for a long time now. Amazon has never included Paypal because Amazon considers Paypal as a competitor directly and not directly. If you use Amazon you have noticed this company is not accepting any payment processor. They accept only Visa/Mastercard, gift cards, etc.
They have already Amazon Payment that they struggle to be adopted so I don't think they are ready to create their coin anytime soon.