Eh. And yet, every single person I know has a ukulele, and can play more songs, more quickly, and more adeptly, than almost everyone I know with a guitar.
I'm a bass player. Have been since I was 12. At the peak, I had 15 bass guitars, even custom-made ones, a 7-string monster, fretted, fretless, acoustic, electric, whatever. They were beautiful, and I played them all. Some more frequently than others.
People make music with whatever is at hand.
The whole Americana-folk revival thing has increased the number of banjo and accordion players 1000-fold, and the marching band thing has made the trombone cool again.
If there are fewer people playing guitar for a while... so what?
People are still making music, using whatever tools are available to them, and those tools are expanding and far easier to obtain.
The fact is that buying shit at Guitar Center or Sam Ash has always been a fucking horrorshow. You had to deal with some whacked-out lead singer metalhead who played on Tuesday at the local rock club with 7 people in the audience, and was bitter that your mom and dad were buying you a guitar. Salespeople would pounce on you the moment you walked into the store. All you wanted to do was try out a bunch of instruments and see if one "talked" to you... and Larry Leather would hover over you, constantly tousling his hair to make sure it stood up high on top.
When I was a Ghost Tour Guide in Pike Place Market, working evenings to make a little more money before my own business could support itself, one of the other tour guides was this guy Jim. He'd found a little place to open up a guitar store, but the building needed way more renovations, so he got a job with us to make some more money for renovations.
Within 2 years of opening his business, he had purchased the entire building, and is doing pretty fucking well: The Seattle Guitar Store
Maybe Sam Ash and the Guitar Center need to learn basic customer service, and stop being subservient to Fender and Gibson.
Shit, Georgetown Music is doing great as well, selling used instruments and equipment at rock-bottom prices. I walked in there last month and saw one of my old bases hanging on the wall for sale!
Oh. What about the Trading Musician in Seattle, that is packed wall-to-wall with quality used musical equipment at good prices, and a wonderfully knowledgeable staff?
"Waaahhhhh! Millennials don't want to be patronized and sold crappy mass-produced generic shit from soulless automatons in sanitized soulless stores next to the malls they don't go to! It's the millennials fault our cynical piece-of-shit business model sucks!"