The problem with multichannel is that it would struggle terribly to spread enough to make it convenient to publish multichannel music by default, how many people would have the space, money and patience or interest to install a multichannel system at home? Many people have great difficulty finding the space and a position at least decent for two small bookshelf speakers.
Multichannel music could also be qualitatively better than stereo, I have no doubt about it, but I don't think it will ever go much beyond the niche, due to the objective difficulty of spreading such a complex, expensive, space-demanding and compromise-intensive system in a normal home.
You are right about how most people in the world would not have the space, the money, the patience, or the interest to install a multichannel system at home, but that is not the decisive factor if multichannel music will be widespread or not. What will decide the future of Atmos for music is how it is received by the headphone-listening world which is the large consumer market for music listening nowadays, and at this point, it seems like many consumers like what they hear with immersive audio for headphones. As long as this trend is going on and if it's here to stay, all the audio nerds who are prepared to install multiple speakers in their homes will be able to take part in all that, no matter how "niche" it is with such audio systems in regular homes. The popularity of Atmos for headphone listening is like a "Trojan horse" for the listeners of multi-speaker systems.
All very true, but the same can be said of stereo today.
Back in the 70-80s, everyone had a receiver and a pair of speakers in their home capable of a nice stereo playback.
No longer, it's sadly only the tiny niche of the folks like us that care about this stuff, 2 or 16 channels.
Joe Sixpack has a little Sonos or Soundbar with some weird AI build in, to create phasey sounding music all around the room that has
no relation to what the artists & engineers tried to convey. Stereo is just a word to them they don't even understand the reasoning for.
The only reason much of interest lives today is the Home Theater group which gained a big boost during COVID times.
OTOH, todays leading recording engineers like Clearwater, Wilson, Parsons, Taylor, so many more, along with the artists
they record, are hugely into and excited about the creative options open to them for recording in 5.1 and Atmos. So along with
straight stereo, I believe multich will continue to expand and grow, it being irrelevant that mostly no one cares.
For those not paying attention, the multich market has exploded over the decade, at a rate that I haven't been able to afford the
flood of music I would have liked to own. Thankfully streaming has partly filled the gap, unfortunately in a mostly lossy manner, at least for now.