I used to sell pianos. One of the guys I worked with in that store is a friend and still in piano sales. He gets calls every day from people wanting them to just "come get" their "grandma's piano". Most of them have been trying to sell it for months on Craigslist for even as little as $100. Many times my buddy goes to see the piano and then turns them down. He refuses to take the piano, even for free, because it is....literally....worthless. The disposal of the item costs more than the item is worth. Yes, virtually EVERY household had a piano or guitar at some point. Now they simply don't.
My 8 year old is interested in piano lessons. I wouldn't dream of getting an acoustic piano. Digitals have great actions and sound amazing. Never mind that studies have shown when children are able to practice with headphones they practice longer and stretch themselves more because they are not afraid of anyone else hearing their mistakes.
Back on the more specific topic, I taught bass lessons in the early 2000s. I had 16 slots most of the time but had to expand my lesson times and certain points because I was booked solid. The two guitar teachers were even more booked. These days, the same store still has lessons. The one guitar teacher has 10 students who no-show all the time and he teaches one bass player. That probably says as much about internet lessons as anything. But it says something.
The only thing I do know is that the new guitar/bass market can't simply keep growing. It just can't. Less people are playing guitar or bass. Of those, many of them like "old looking" guitars and basses. Reverb, Ebay, GC used, and Craiglist make it easier than ever to connect with a used guitar or bass of your dreams hundreds of miles away for hundreds less than new. Baby boomers who own a good percentage of the vintage instruments are getting to the age of no longer playing. Those guitars and basses will enter the market in a few years to a decade and we will see a small flood of vintage instruments. In my view, there are thousands and thousands of 60s, 70s and 80s guitars and basses sitting in cases in closets that haven't been touched in years. And when "Uncle Bob" passes away, or moves to the small assisted living condo, those guitars and basses will hit the market like a sledgehammer.
I see the same things happening in the firearms, model trains, vintage/tube electronics/ham radio, vintage cars, and other markets as well in the near future. "Uncle Bob" also has a 67 Nova SS, a WWII M1 Garand, an N scale model train still in the box, a vintage Yaesu tube ham radio, etc. All of these items will be in less and less demand and be "let go of" more and more. My daighter is 8 years old. Virtually NONE of her peers will EVER want a vintage Nova, old military rifle, old train set, old ham radio, old guitar, etc.
These are simply my opinions. Take them for what they are worth.
I was born in 1963 and had accordion lessons. It was indeed a thing. My slightly older friends were more serious players in their day.
Middle class homes all used to have pianos as well.
I was born in '61. No accordion in our house but I did play one at a friend's house at some point. We did have a piano though, and my first piano teacher (age 8) was an old jazz trumpeter who of course played piano. He'd taught my older brother (13 years older than me), and even my mom. Sadly he passed away about 9 months into my study. He had me doing boogie woogie and stride pretty quickly. I posit that had he not died I likely would have ended up a more serious piano player rather than the relative hack I am today.
We have a piano in the house, and my son was forced to study an instrument until he graduated high school. He could pick whatever he wanted, but the rule was he had to do something other than play computer games. He'll thank me for it later.
stylish dresser
The used piano market has essentially collapsed, except for the fancy stuff. I bought a used console in excellent condition recently for 150 bucks, and probably could have talked them down, but they were selling it for a vets charity and I felt bad about it.