As a kid, Radio Shack was my favorite store and I often went there to buy parts and to learn about new components. Now I'll admit that I buy big ticket items online (better selection, ability to compare and research alternatives, avoid a trip to the mall). Radio Shack is the place I go for parts once a year when something breaks. It seems that they are the "convenience store" of electronics. If you want tools, there are home improvement stores, if you want cell phones there are cell phone stores, but if you have a shopping list with a variety of items then Radio Shack gets a visit.
I guess it's like Kodak--when change came, there was little they could do about it, despite what all the pundits said: "they didn;t adapt, even though they invented the digitla camera." Fact is that their entire business model was based on selling consumables like film and chemicals and processing, not one-time items like cameras (those were almost an incidental business for them). And Kodak had lots of IP and patents, unlike Radio Shack, so RS is in a far more precarious place.
For the vast majority of folks, all they need "right away" might be cable assemblies (cable+connector) or batteries. Radio Shack can't make a profitable business from those items alone. For the serious hobbyist or DIY person--and there are some out there--it's easier, smarter, and cheaper to get your BOM filled online if you can't get to a Fry's or equivalent nearby. Radio Shack is stuck in the gap in the middle, not a good place. And the "iconic" name sure doesn't help, either.