I think it's a negative thing if they did start accepting bitcoin as a payment method. bitcoin is unstable and people would lose so much paying with it .
But bitcoin would be useless if no ones accepts it, what are you going to do with your btc once that they become useless? are you going to eat them all?
Amazon will never accept bitcoin, it is impossible, and if it really happens, the massive hype that bitcoin could have would be amazing.
Amazon is greedy as fuck, probably they will start their own crypto, or just tokens, but the are going to ride their own crypto, i am sure of that