What I've found is when I do finish a book and I do not dive directly into the next one, my consumption of media on the Internet tends to widen the length of time I spend between books. This has led me to essentially read in spurts, where I'll devour 3-5 books in a quick span and then "catch up" on all the media I've been missing on the Internet. This is in sharp contrast to my younger days when all I would do is read, and I do find myself missing the time when I didn't feel the urge to know what is happening on the internet at all times, i.e. "missing out on pop culture." I've been working on diminishing that though, the internet will never replace books for me.
This absolutely happens to me as well, though the media I consume online is probably 98% written word (excluding music, which I also devoured as a youth and continue to). I don't read less as a result, -just fewer books and more short-form. I do believe the quality of what I read overall has declined significantly, although to be fair, I could go months reading books years ago before finding one that was transformative and blew me away. I may be looking back with rose tinted glasses to some degree.