A company like Amazon using Bitcoin would be huge because not only it is the biggest e-commerce/retailer in many countries it has many other service such as AWS ect so it will push the adoption of Bitcoin by the average joe several folds, But there are several issues such as the votality of the currency and regulation and nowadays fees and confirmation issues. (although amazon them selves could speedups the confirmations)

In France there is no Bitcoin option heck they just started accepting 4x payment a couple of days ago so we are far from having bitcoin as a method of payement here

Anywa for me big companies accepting bitcoin would render Bitcoin as popular as paypal in my opinion.