What a complicated question! Just a couple thoughts.
Appointments. I resist them, though I have shopped and purchased gear from brick/mortar. Why? It ramps up the pressure. It almost feels like an engagement. For me, personally, if I'm going to listen to gear that costs thousands, I am really not going to go to a store with an intention to buy. I'm not intending to tire-kick, but I need to feel at ease in order to listen objectively. I have to imagine there are others like me. If everything comes together, and service can help, here, I will buy and it will be at that store. Their expertise deserves to be paid for.
Specialized stores still exist -- mattress stores, jewelry stores, cheese shops, etc. Those lines have found ways to give customers a reason to shop with them, rather than at a supermarket or Macy’s. If hifi could get itself disentangled from consumer electronics, it might stand a chance. But since most people listen ubiquitously (e.g. while they’re cooking, commuting, etc.), this is a challenge. In some ways, it might take the music industry to push this change, but since they want to push content, they couldn’t care less if it was coming across bluetooth headphones.
Best Buy -- upped their lines a few years ago. It’s not hifi enough for me, but there are some good things there. Yes, it’s still a terrible space to evaluate audio equipment, at least one can fall into it while shopping for something else. If HiFI could become part of, say, Nordstroms, there might be a chance for people to both make it a destination and also fall into a shopping experience for hifi.
Combining online with in-person. The Music Room is building a listening space after years as an online seller. It seems that online retailers could follow suit and build or rent spaces to demo gear. That way, when nothing else is happening (e.g. foot traffic) they could just do the online sales/service work they’d be doing anyway.