I don't have a lot of inner details about amazon but I do know that they have peaked already as far as retail goes. I don't know when, I just know its happened already.
Amazon is no longer any of the following:
The cheapest deal
Filled with reliable reviews
Filled with trustworthy companies
And on top of that, their product search page is to the point where not even the advertisers are having a good time. The end users (buyers) stopped having a useful interface a while before that.
Its easier now for me to avoid amazon simply because they aren't the best deal by nearly any metric any more.