EC2 and S3 are't trivial to replicate. Moreover, consider the entire platform and the dominant position of Amazon. Amazon is the Microsoft of yore- they actively cannibalize any profitable service on their platform. How many products is AWS, now? Perhaps 50, or 100? Can anyone reasonably migrate off AWS after integrating with even 5 or 6 of them? Did the profits of Office go to zero as it was copied and handed out for free a dozen times over? Amazon will be making bundles of money with AWS for a long time to come.
For all intents and purposes, Microsoft Azure and Google Cloud Platform have already replicated EC2 and S3, and every other feature they think is worth it. The price war in 2014 was pretty brutal (unless you're a customer, of course!) and it's not going to slow down in 2015.
And as people move away from 'raw cloud metal' to whatever the layer du jour is, what's underneath will matter less and less.
