I think the only realistic scenario where bitcoin is adopted by Amazon is if we see some kind of partnership between Amazon and Bitpay, or some other payment processing companies that supports cryptos.
I don't think Amazon would integrate bitcoin just by itself.
I think you're right, at the very least you'd have to be verified in some way, Bitpay would be a good match.
I also think this is how altcoins will go mainstream as well. Once the big eCommerce giants start making deals with the crypto payment processors, you will start to see altcoins being used for purchases. Exciting stuff.
Yes, also lot of those altcoins are trying to do the instant payment thing with or without companies accepting cryptos. There's also crypto ecommerce apps coming (Particl).
One way or another you'll soon be able to spend them anywhere on anything, instantly.