Every such transaction will likely be a cheaper and more economic benefit for the party that receives bitcoin. The purchasing power increases over time. And everyone will want to use it. Simple. I do not expect amazon to allow bitcoin. However, I expect bitcoin to be used in other parts of our lives in the next decade
You cannot simply say that amazon will not be allowing bitcoin, may be if we have a better scaling solution and there are more demands from the customers we might see them accepting bitcoin payments, we had more adoption in 2013 and it died off when the transaction charges started moving higher and once that is sorted we will see adoption by these merchants.