Amazon seems like one of the biggest companies in the whole world right now, it is not that easy to put biggest company in the entire world to get out of business thanks to couple of new options. Standard oil was seen as the biggest company of its time and had to be torn apart for monopoly reasons, the companies that came to be after it was torn apart right now holds over a trillion dollars in value, even shredding it to pieces didn't hold those companies low.

Amazon will always be one of the big players unless something huge happens to it. Of course, decentralized markets could get a share out of it and certainly rival it but just because Amazon would have some competition at the top would mean it will go down, it will just soar with them together instead.