Or put another way, whether Amazon is willing to cede any of its cost advantages to some retail brand.
Not really because still always pay for what you provision. If you know your requirements well enough then doing your own hosting can be a lot cheaper than Amazon which has to charge a premium because it provisions more.
Going with a provider like Amazon for this kind of service also leaves you at their mercy: you cannot really use the market as you might like as migrating several TB or EB of data to another provider doesn't happen at the drop of a hat.