As much as we lament the demise of brick and mortar retailers, Amazon is a genuinely amazing company. As an example: my computer graphics card has been acting up for several weeks, causing screen locks and reboots. I could get in my car and drive to Best Buy to get a new one, but Amazon has every graphics card ever made, typically charges about 2/3 as much as Best Buy, and will deliver it to my house in less than 8 hours. For all I know, it's coming off the shelf at Best Buy and being driven over here by a contractor, for less money and less effort to me than if I had driven to Best Buy to get it for myself.
If the future of retail includes paying less money for a wider selection of goods that magically appear at my doorstep in less than a day, then the Sears/MWard/Penny's model has been eclipsed. We don't need them, just like we don't necessarily need cable companies in the era of Netflix and we don't need tiny hotels in the era of AirBnB and we don't need physical newspaper delivery in the era of online news. These old-style service companies have to find a way to stay useful and relevant if they want to compete with evolving superior alternatives.
Best Buy is hanging in there, for example, by catering to people (largely senior citizens) that want to physically touch things before they buy them, and have a salesperson walk them through the process. Good for them, that's a value-added way to keep your store useful, but for people who already know what they want to buy and want the lowest price and the most convenience, amazon is a better option. I have no idea if amazon's current stock prices is in any way appropriate, but I still think they're a great company. Well, great for consumers and investors anyway.