>However, I suspect that niche is nowhere near big enough to support Radio Shack's size.
This is my thinking as well. Retail is brutal. Each shelf needs to being in x amount of money as space is limited. You have to worry about staffing, taxes, inventory, etc and knowing the full time that amazon or monocable beats you everytime on your high-margin items must be scary.
All these geek friendly narratives keep getting built (oh if they did this or if they did that) but I think the reality is that retail only fits certain business models. Radio shack not longer fits in one of those models since the rise of the big box store and the web. We're talking, what, 5 to 10 stores per market? That's a lot of infrastructure to support and big bills to pay every month. Even during its heydey it was a dumping ground of low quality stuff, namely its Realistic house brand, and its own computer brand which never really competed with its peers like the Apple //e or c or VIC20/C64. I think there's more than little brand nostalgia applied to Radio Shack. Its always been a poor business and its once formidable component supply wasn't ever enough to keep it afloat.