This might just be the end of brick and mortar

I'm pretty much in agreement with Mitch2 (did you mean tailwind, toward demise, or headwind, to buffet their advance?)
We have short memories, I think. Even in the heyday of the 'stereo store' (before we needed to distinguish so-called 'Brick & Mortar' from its virtual counterpart), there were a lot of shortcomings with the conventional dealer 'model'- dealers could not conceivably carry every line, couldn't account for synergies among brands they didn't sell (not sure they did it effectively even among the brands they did), and wanted you to buy what they were selling, not what you thought you wanted. Forget the attitude issues, the lack of support, and the limited knowledge- most dealers could not deliver what they promised, and that's why the premium charged wasn't worth it to a considerable number of customers. Today's high end dealer doesn't need a retail store front, operates by appointment, makes house calls, provides support, loaners and takes good care of long term customers. That costs money and there are probably only a small handful of dealers in the States that are able to do that. The rest- well, remember when 2 channel stereo basically crashed as a consumer product, and most dealers turned to home theatre as a revenue stream? And now that you can buy most of that online unless you are looking for a large 'install,' they are back to where they were- yes, probably a small handful have enjoyed the 'bump' from renewed interest in analog, but I gotta believe that the business has been suffering at the middle price point for decades. (No animus against dealers, btw, just an observation, based on a fair amount of experience).

Oblgny- I don't know if you remember what made the Stereo Exchange special in the early days- it was a bazaar of used high end- you could walk in and find the last flavor of the month at a decent price compared to retail or the usual discount. I bought tons of stuff from Dave in the old days- after the used market shifted to A-gon, the store lost that mojo. And, SE shifted to home theatre, as a lot of dealers did. I have fond memories of the place and used to enjoy some of the staff, who have moved on in different directions. I still speak to Dave occasionally- he is a good guy.

Schubert- true, and since my niece, a millennial, seems perfectly content to watch a film or listen to music on her computer with a small ancillary sound system, this stuff has functionally replaced hi-fi and even 'home theatre' gear, rather than just being a diversion to something else.