I believe there are a number of entrenched players in this space already. They're called "shops".
The elegance of Amazon is its logistics.
Hah. You'll be looking for a lot longer at any of Amazon's stores.
This is the model that Amazon will have to beat. And the only way it can do that is through offering a better selection. Which should be possible since Amazon won't have aisles to stock.
Also if Amazon become good at having the items ready, it becomes a very different experience than traditional shopping.