Conversion rate is all that really matters in Online Marketing.
Everyone continues to have concerns about Amazon; but Amazon need to be and are being treated by those who know the space as another competitor that needs to be tamed. Ebay don't seem to have too much concern re: Amazon and I can't see Amazon putting ebay to shame.
The Retail distribution model in such a short period has rapidly changed. Who knows where we will be in 5, 10 or 15 years time.