Earlier quoted context omitted.
People said this 20 years ago about Microsoft. They were king of the PC, imposing a Windows (and Office-) tax on every other business. They were trying to extend that dominance to the internet: Internet Explorer, CitySearch, Expedia, MSN portal, MSN Shows, MSN Messenger, you name it. They were building interactive TV, software for cars, and a mobile phone platform. For a while they were building a bill presentation a…
So you're saying Amazon is no different -- they'll try and take on nearly every industry, but will really only have one core competence in 20 years?
I think that 20 years ago people couldn't see a competitor coming along that could disrupt Microsoft, because they were so big and into everything.
But that's because no one foresaw the coming of the smartphone. Microsoft is still king on PCs, but the PC market has been in decline for years. Back in the early 00's no one predicted the iPhone and Android, and what a massive impact they would have on the PC market.
I would argue that Microsoft actually has two core competencies today: Office, and services (e.g. Windows/Azure). But yes, they definitely went from "king of everything" to "well enterprise still uses them" remarkably quickly.
tl;dr - Something will likely disrupt Amazon, but it's difficult for us to predict what that will be until it happens