No, I don't think readers' attention spans have diminished. I think that's typical millenial-bashing nonsense. I think there are now so many books available at the click of a button, for a few quid/dollars/whatever, that readers have no incentive to stick with books that bore them. If I start a book and find myself bored, it takes three seconds for me to backup to my Kindle homepage and open another one. 10 years ago, I'd have paid 3x as much for that paperback and would have to go to a bookshop to buy another one. I finished many more medicore books 10 years ago. Was I better for it? No. I've listened to all 24 hrs 38 minutes of The Woman in White on audiobook multiple times. It's long-winded, rambling, in the typical Victorian fashion of using 20 words where 2 would do. I love it. My attention doesn't wander. My attention span is just fine. But I won't last 24 minutes on a book that doesn't engage me, and why should I?