I found this article the other day and found it very interesting.http://www.wired.com/2015/03/amazon-unlimited-everything-cloud-storage/
Like you, I see Amazon (like Facebook) as one of the 800lb gorillas on the Internet block, and very unlikely to disappear any time soon.
So, I've opened an account. I chose this offering:https://www.amazon.com/gp/drive/landing/photos/ref=nav_shopall_GW_US_I_D_ACD_GNO_UPS_413476
Yes, it's basic, but so is an external drive sitting on your desk.
The problem is the time it takes to upload the first time round - and I'm only uploading RAW files, for the following reasons.
I take the view that if a client comes looking for a file I shot, for example, 4 or five years ago;
1. They should have the file re-edited on the most up-to-date version of the software I'm currently using.
2. They should have to pay a fee for access to something I've been storing on their behalf for all that time.
3. RAW, obviously, takes up less space.
Ideally, I would like uncontested broadband (i.e. the upload speed being the same as the download speed) which mine isn't. So, I'm setting the computer to upload overnight and leaving it. But, I think that I'll only upload a few years first (I started shooting digital professionally in 2006) to see how the service goes. If I like it, I'll then upgrade my broadband, even if only for a month, to upload the rest.
I would be interested in the views of others.