I cannot help thinking that it depends on where you look.
People, even young ones, still check out books from the libraries, classics and even fiction written fifty years ago.
At the bookstore, I find that the market has moved form slim 180 page books to most books being above 400 pages nowadays.
I have been looking for a young person who enjoys my kind of books so as to leave all mine to them when I die - and an acquaintance introduced me to his 22 year old daughter...who told me she loves big books, especially if they are more than one book. When she saw my books with a number of them being of 800 pages and maybe 8 volumes, she was thrilled.
I think our problem is we are being affected by spending so much time among those who live on the web.
I would rather write for those who live lives of their own.
:)
Again, your observations are so perceptive, Alex. I agree, being around social media sites prejudices you and you think everyone is just interested in a sound bite, a cat video or a two-minute read. It's so easy to get jaundiced and I tend to be easily exasperated. It's really hard to find an on-line forum where you can post, get paid and get some feedback from readers. Steemit used to be like that but it's a mere shadow of what it was.