Amazon will not accept bitcoin or any other crypto any time soon.
Amazoncoin is far from a coin, except for the name, it's like a voucher, I guess they tried to used the word coin to make it "rebrand" the voucher thing.
Overstock, as a first, will be a big experiment, we will see how it goes.

By the way, why do you think Amazon pays the standard rate to plastic? They must have a better deal