BB is in a slightly different situation than other MCX members. BB is basically an overpriced showroom for online retailers like Amazon, and has been reduced to sub-leasing floor space to manufacturers to reduce overhead costs. Apple may have put the screws to BB by threatening to pull displays/leased space from stores if they didn't accept ApplePay. BB accepting ApplePay is a sign of desperation in an attempt to stop the bleeding of customers to other BnM (some are also MCX members) and online retailers. BB will likely go the way of Circuit City and soon to be bankrupt Radio Shack.
I completely agree with you and for the longest time (well ever since Circuit City went out of business), I have been wondering when it would be BB's turn to go. However, I think that as the need for technology continues to grow the need for hardware (e.g., router, hard drive, phones, laptop etc...) as well as services, repairs and such will continue to grow as well.
With that said, one can argue that why are people still shop at BB when online stores such as Amazon are cheaper and almost just as convenient. I think the answer is that like everything else in life, not everyone is a wizard in what they need to accomplish, also not everyone has a friend that knows a thing or two about technology. For some people shopping for a computer or a router is as daunting as getting a car, and quite frankly probably even more confusing at times. At least with cars people can relate more easily, try explaining HP vs. CPU speed to an older person.
So giving that the need for hardware/service are still required, I think the market has now reached an equilibrium. With the demise of Circuit City, and Radio Shack, I think the customers are now redirect back to BB. So even thought they lost customer base to online retailers, they gained by out surviving other tech stores.
Lastly, have you seen the price they charge to "repair" computers? Most of the issues I bet they just ended up running a restore using the factory reset which takes about 10 minutes to do and just leave the computer running for the next hour or so. And frankly if it's really a hardware problem, BB would most likely have to send it back for repair anyways. I doubt they have much ability to replace a laptop's mother board or other similar fixes.