Alibaba will not become bigger than Amazon. They have too many skeletons in their closet with the selling of counterfeit goods and other shady business practices that it will be hard for people to trust them like they trust Amazon. It will take many, many years before they are a threat to Amazon.
No, I don't think any company will be bigger. I believe that Amazon.com is the biggest and best company of its kind. I don't think that Alibaba can really compete with Amazon on a level playing field. I think the company is more of an china institute rather than a worldwide one.
Alibaba is overrated. It is great for people interesting in making money for China and for wholesalers, but most Americans don't know anything about Alibaba and most will not look into the site because it is not oriented towards the typical consumer. Alibaba will surely sell, I just don't think it is going to be as big of a deal as Amazon.
Considering I do most of my shopping online, I think that I have not heard of this means it's really not all that big. I don't think it's going to get bigger than Amazon, but who knows. If it does I guess we will all find out in the future.